Develop Reference

Why can't I return true? am I making a mistake in the database query part?

I have tried all kinds of combinations since morning but I can't return any true value. The information I entered is completely correct.
Help me pls why can't I return true? am I making a mistake in the database query part?
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
import java.sql.ResultSet;
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* #author seyme
*/
public class para_ekle extends javax.swing.JFrame {
private boolean ahmet;
/**
* Creates new form para_ekle
*/
public para_ekle() {
initComponents();
}
static boolean ekle = false;
public void kontrol() throws SQLException{
Connection connect = null;
dbbaglanti db = new dbbaglanti();
connect = db.getConnection();
Statement oku = ( Statement) connect.createStatement();
String cekilenid = idtext4.getText();
int cevrilenid = Integer.parseInt(cekilenid);
String sifrebilgisi = sifretext4.getText();
String tutarbilgisi = idtext4.getText();
int cevrilentutar = Integer.parseInt(tutarbilgisi);
try {
}catch(Exception e){
JOptionPane.showMessageDialog(null, "Bilgilerde Bir Hata Bulunuyor!");
}
ResultSet rs;
rs = oku.executeQuery("SELECT count(id) as \"giris\" FROM dbkullanici.kullanicilar WHERE id ="+ cevrilenid +" && sifre = '"+sifrebilgisi+"'" +";");
while (rs.next()) {
int id = rs.getInt("giris");
if(id == 1){ boolean ahmet = ekle == true; } else if (id == 0 ){boolean ahmet = ekle == false;}
}
if(ahmet == true){
erortext.setText("verilerdogru");
}else if(ahmet == false){
erortext.setText("Bilgileriniz Veritabanımızda ki veriler ile eşleşmedi");
}
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
jLabel6 = new javax.swing.JLabel();
idtext4 = new javax.swing.JTextField();
sifretext4 = new javax.swing.JTextField();
jLabel7 = new javax.swing.JLabel();
jButton1 = new javax.swing.JButton();
jLabel3 = new javax.swing.JLabel();
tutartext = new javax.swing.JTextField();
erortext = new javax.swing.JLabel();
jButton2 = new javax.swing.JButton();
jLabel4 = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setFont(new java.awt.Font("Segoe UI Black", 1, 36)); // NOI18N
jLabel1.setText("ISSEY FİNANS SİSTEMİ");
jLabel2.setFont(new java.awt.Font("Ink Free", 1, 14)); // NOI18N
jLabel2.setText("ISSEY ile paralarınız daha değerli");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap(37, Short.MAX_VALUE)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 428, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(32, 32, 32))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 214, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(128, 128, 128))))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(22, 22, 22)
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 18, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
);
jLabel5.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
jLabel5.setText("Hesap Şifreniz: ");
jLabel6.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
jLabel6.setText("Hesap İd Numaranızı Yazınız: ");
idtext4.setText("jTextField1");
sifretext4.setText("jTextField2");
jLabel7.setText("İd Numaranızı Bilmiyorsanız Kullanıcı listeleme panelinden görüntüleyebilirsiniz.");
jButton1.setText("Ana Menü'ye Dön");
jLabel3.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel3.setText("Eklemek İstediğiniz Tutar");
tutartext.setText("jTextField1");
erortext.setForeground(new java.awt.Color(255, 0, 0));
jButton2.setText("Para Ekle");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
jLabel4.setForeground(new java.awt.Color(102, 102, 102));
jLabel4.setText(" Para Eklemi işlemi için tüm bilgileri büyük küçük harf ve boşluk dahil doğru girmelisiniz.");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(erortext, javax.swing.GroupLayout.PREFERRED_SIZE, 390, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(55, 55, 55))
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel7)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel6, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel5, javax.swing.GroupLayout.PREFERRED_SIZE, 188, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 142, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(26, 26, 26)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(idtext4)
.addComponent(sifretext4)
.addComponent(tutartext, javax.swing.GroupLayout.PREFERRED_SIZE, 124, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 119, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 118, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(8, 8, 8)))
.addGap(61, 61, 61))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 408, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(23, 23, 23))))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel7)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel6, javax.swing.GroupLayout.PREFERRED_SIZE, 34, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(idtext4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel5, javax.swing.GroupLayout.PREFERRED_SIZE, 27, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(sifretext4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(tutartext, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jLabel4)
.addGap(16, 16, 16)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(erortext, javax.swing.GroupLayout.DEFAULT_SIZE, 50, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
try {
kontrol();
} catch (SQLException ex) {
Logger.getLogger(para_ekle.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(para_ekle.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(para_ekle.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(para_ekle.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(para_ekle.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new para_ekle().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel erortext;
private javax.swing.JTextField idtext4;
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JLabel jLabel6;
private javax.swing.JLabel jLabel7;
private javax.swing.JPanel jPanel1;
private javax.swing.JTextField sifretext4;
private javax.swing.JTextField tutartext;
// End of variables declaration
}

Java Swing jLabel java.lang.NullPointerException [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 2 years ago.
I have a class Hangman and one class GUI. Hangman class for the process. So, I want to passing the value String form Hangman class to jLabel in GUI. When I run the project and I am strungling in java.lang.NullPointerException even I wrote the right code. When user click start. The value from class Hangman will show to the jLabel
Hangman class
package hangman;
import java.util.*;
import java.io.*;
import java.awt.*;
public class Hangman {
String filename = "words.txt";
String[] wordList;
String[] wordBanks = {"DISAVOW","KEYHOLE","QUIZZES",
"WHOMEVER","ZIGZIG","WHEEZY","UNWORTHY",
"WHIZZING","JOCKEY","MICROWAVE"};
String[] answer;
int index;
String[] resultarray;
StringBuilder stringbuilder = new StringBuilder();
String resultstring;
public Hangman()
{
initialComponent();
}
public void initialComponent()
{
index = randomIndex();
answer = wordBanks[index].split("");
resultarray = new String[answer.length];
for(int i = 0; i < answer.length ;i++)
{
resultarray[i] = " _ ";
stringbuilder.append(resultarray[i]);
}
resultstring = stringbuilder.toString();
}
public int randomIndex()
{
int rand = 0;
// define the range
int max = 10;
int min = 0;
int range = max - min;
// generate random numbers within 1 to 10
for (int i = 0; i < 10; i++) {
rand = (int)(Math.random() * range) + min;
// Output is different everytime this code is executed
//System.out.println(rand);
}
return rand;
}
public void printWord()
{
System.out.println(wordBanks[randomIndex()].toString() + "|" + wordBanks[randomIndex()].length());
}
public void initialWord()
{
int random = randomIndex();
//answer = new String[random];
answer = wordBanks[random].split("");
for (int i = 0; i < answer.length;i++)
System.out.println(answer[i]);
}
public static void main(String[] args) {
// TODO code application logic here
Hangman hangman = new Hangman();
GUI gui = new GUI();
gui.setVisible(true);
}
}
GUI class
'''
package hangman;
public class GUI extends javax.swing.JFrame {
Hangman hangman;
/**
* Creates new form GUI
*/
public GUI() {
initComponents();
//defaultResult();
}
public void defaultResult()
{
jLabelGuess.setText(hangman.resultstring);
}
#SuppressWarnings("unchecked")
private void initComponents() {
jFrame1 = new javax.swing.JFrame();
jLabel1 = new javax.swing.JLabel();
jButtonStart = new javax.swing.JButton();
jButtonA = new javax.swing.JButton();
jButtonB = new javax.swing.JButton();
jButtonC = new javax.swing.JButton();
jButtonD = new javax.swing.JButton();
jButtonE = new javax.swing.JButton();
jButtonF = new javax.swing.JButton();
jButtonG = new javax.swing.JButton();
jButtonH = new javax.swing.JButton();
jButtonI = new javax.swing.JButton();
jButtonJ = new javax.swing.JButton();
jButtonO = new javax.swing.JButton();
jButtonP = new javax.swing.JButton();
jButtonQ = new javax.swing.JButton();
jButtonR = new javax.swing.JButton();
jButtonK = new javax.swing.JButton();
jButtonS = new javax.swing.JButton();
jButtonL = new javax.swing.JButton();
jButtonT = new javax.swing.JButton();
jButtonN = new javax.swing.JButton();
jButtonM = new javax.swing.JButton();
jPanel1 = new javax.swing.JPanel();
jButtonO1 = new javax.swing.JButton();
jButtonP1 = new javax.swing.JButton();
jButtonK1 = new javax.swing.JButton();
jButtonL1 = new javax.swing.JButton();
jButtonN1 = new javax.swing.JButton();
jButtonM1 = new javax.swing.JButton();
jLabel2 = new javax.swing.JLabel();
jLabelAtemp = new javax.swing.JLabel();
jLabelGuess = new javax.swing.JLabel();
javax.swing.GroupLayout jFrame1Layout = new javax.swing.GroupLayout(jFrame1.getContentPane());
jFrame1.getContentPane().setLayout(jFrame1Layout);
jFrame1Layout.setHorizontalGroup(
jFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
jFrame1Layout.setVerticalGroup(
jFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
jLabel1.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel1.setText("Welcome to Hangman");
jButtonStart.setText("Start");
jButtonStart.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonStartActionPerformed(evt);
}
});
jButtonA.setText("A");
jButtonB.setText("B");
jButtonC.setLabel("C");
jButtonD.setText("D");
jButtonD.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonDActionPerformed(evt);
}
});
jButtonE.setText("E");
jButtonF.setText("F");
jButtonG.setText("G");
jButtonH.setText("H");
jButtonH.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonHActionPerformed(evt);
}
});
jButtonI.setText("I");
jButtonJ.setText("J");
jButtonJ.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonJActionPerformed(evt);
}
});
jButtonO.setText("O");
jButtonO.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonOActionPerformed(evt);
}
});
jButtonP.setText("P");
jButtonQ.setText("Q");
jButtonR.setText("R");
jButtonK.setText("K");
jButtonK.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonKActionPerformed(evt);
}
});
jButtonS.setText("S");
jButtonS.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonSActionPerformed(evt);
}
});
jButtonL.setText("L");
jButtonT.setText("T");
jButtonN.setText("N");
jButtonN.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonNActionPerformed(evt);
}
});
jButtonM.setText("M");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 256, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 0, Short.MAX_VALUE)
);
jButtonO1.setText("O");
jButtonO1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonO1ActionPerformed(evt);
}
});
jButtonP1.setText("P");
jButtonK1.setText("K");
jButtonK1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonK1ActionPerformed(evt);
}
});
jButtonL1.setText("L");
jButtonN1.setText("N");
jButtonN1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButtonN1ActionPerformed(evt);
}
});
jButtonM1.setText("M");
jLabel2.setText("Atemps left:");
jLabelAtemp.setText("jLabel3");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap()
.addComponent(jButtonN1, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonO1, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonP1, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(189, 189, 189))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(57, 57, 57)
.addComponent(jButtonK1, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonL1, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonM1, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addComponent(jButtonA, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonB, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonC, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonD, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jButtonK, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonL, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonM, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButtonN, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonO, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonP, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonQ, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonR, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonS, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonT, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addGap(163, 163, 163)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabelGuess, javax.swing.GroupLayout.PREFERRED_SIZE, 287, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addComponent(jButtonE, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonF, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonG, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonH, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonI, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButtonJ, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(18, 18, 18)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(192, 192, 192)
.addComponent(jLabel1))
.addGroup(layout.createSequentialGroup()
.addGap(20, 20, 20)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel2)
.addComponent(jButtonStart))
.addGap(18, 18, 18)
.addComponent(jLabelAtemp)))
.addGap(155, 155, 155)))
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
.addComponent(jLabel1)
.addGap(35, 35, 35)
.addComponent(jLabelGuess, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 37, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButtonA)
.addComponent(jButtonB)
.addComponent(jButtonC)
.addComponent(jButtonD)
.addComponent(jButtonE)
.addComponent(jButtonF)
.addComponent(jButtonG)
.addComponent(jButtonH)
.addComponent(jButtonI)
.addComponent(jButtonJ))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButtonK)
.addComponent(jButtonL)
.addComponent(jButtonM)
.addComponent(jButtonO)
.addComponent(jButtonP)
.addComponent(jButtonQ)
.addComponent(jButtonR)
.addComponent(jButtonS)
.addComponent(jButtonT)
.addComponent(jButtonN))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButtonK1)
.addComponent(jButtonL1)
.addComponent(jButtonM1)
.addComponent(jButtonO1)
.addComponent(jButtonP1)
.addComponent(jButtonN1))
.addGap(28, 28, 28)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(jLabelAtemp))
.addGap(29, 29, 29)
.addComponent(jButtonStart)))
.addGap(19, 19, 19))
);
pack();
}// </editor-fold>
private void jButtonDActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonHActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonJActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonOActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonSActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButtonNActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButtonKActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonO1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButtonK1ActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonN1ActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButtonStartActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
jLabelGuess.setText(hangman.resultstring);
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
//Hangman hangman = new Hangman();
//GUI gui = new GUI();
//gui.setVisible(true);
/* Create and display the form */
/*java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new GUI().setVisible(true);
}
});*/
}
// Variables declaration - do not modify
private javax.swing.JButton jButtonA;
private javax.swing.JButton jButtonB;
private javax.swing.JButton jButtonC;
private javax.swing.JButton jButtonD;
private javax.swing.JButton jButtonE;
private javax.swing.JButton jButtonF;
private javax.swing.JButton jButtonG;
private javax.swing.JButton jButtonH;
private javax.swing.JButton jButtonI;
private javax.swing.JButton jButtonJ;
private javax.swing.JButton jButtonK;
private javax.swing.JButton jButtonK1;
private javax.swing.JButton jButtonL;
private javax.swing.JButton jButtonL1;
private javax.swing.JButton jButtonM;
private javax.swing.JButton jButtonM1;
private javax.swing.JButton jButtonN;
private javax.swing.JButton jButtonN1;
private javax.swing.JButton jButtonO;
private javax.swing.JButton jButtonO1;
private javax.swing.JButton jButtonP;
private javax.swing.JButton jButtonP1;
private javax.swing.JButton jButtonQ;
private javax.swing.JButton jButtonR;
private javax.swing.JButton jButtonS;
private javax.swing.JButton jButtonStart;
private javax.swing.JButton jButtonT;
private javax.swing.JFrame jFrame1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabelAtemp;
private javax.swing.JLabel jLabelGuess;
private javax.swing.JPanel jPanel1;
// End of variables declaration
}
The message error when I run the application.
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at hangman.GUI.jButtonStartActionPerformed(GUI.java:400)
at hangman.GUI.access$000(GUI.java:12)
at hangman.GUI$1.actionPerformed(GUI.java:96)

It seems that in the GUI class you declare a member variable, Hangman hangman, but you never initialize it. Therefore, the code jLabelGuess.setText(hangman.resultstring); and similar calls will result in a null pointer exception.

In the GUI class, you just only declare Hangman hangman, which mean the class Hangman has never been called to execute or initialized any value. Therefore, hangman.resultstring is null when you called jLabelGuess.setText(hangman.resultstring), since resultstring value is get from Hangman class; and cause Null Pointer Exception error at jLabelGuess.setText() and the function jButtonStartActionPerformed()
You might fix it if you initialize the Hangman class: Hangman hangman = new Hangman(); Or calling the function that initializes the value of resultstring which is hangman.initialComponent()

Awt Components are not shown

I'm developping Library System with Java in awt framework.
If user click add book interface open in same window with different components.For example after clicking,add book menu components removing and add books components added to same window. My problems is after user in section add book if user click menu section,menu component is not shown although components added.Main activity:
public class LibrarySystemInterface extends javax.swing.JFrame implements
PanelWorker {
private FileReaderWriter writer;
private LibraryIterator forCode ;
private Library kutuphane;
private Collection collection;
private int count=1;
private PanelWorker getToWork;
private Library library = null;
private static LibrarySystemInterface instance;
public LibrarySystemInterface() {
initComponents();
writer=new FileReaderWriter("prevent");
kutuphane=Library.getInstance();
}
private void initComponents() {
panel1 = new java.awt.Panel();
label1 = new java.awt.Label();
list1 = new java.awt.List();
label2 = new java.awt.Label();
list2 = new java.awt.List();
ekle = new java.awt.Button();
sil = new java.awt.Button();
ara = new java.awt.Button();
iade = new java.awt.Button();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
label1.setText("Butun Kitaplarin Listesi");
list1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
list1ActionPerformed(evt);
}
});
label2.setText("Odunc Verilcek Kitaplarin Listesi");
ekle.setLabel("Kitap Ekle");
ekle.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
ekleActionPerformed(evt);
}
});
sil.setLabel("Kitap Sil");
sil.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
silActionPerformed(evt);
}
});
ara.setActionCommand("Kitap Ara");
ara.setLabel("Kitap Ara");
ara.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
araActionPerformed(evt);
}
});
iade.setLabel("Kitap Iade");
iade.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
iadeActionPerformed(evt);
}
});
javax.swing.GroupLayout panel1Layout = new javax.swing.GroupLayout(panel1);
panel1.setLayout(panel1Layout);
panel1Layout.setHorizontalGroup(
panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel1Layout.createSequentialGroup()
.addGroup(panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(ara, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(sil, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(ekle, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 171, Short.MAX_VALUE)
.addComponent(iade, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(list1, javax.swing.GroupLayout.PREFERRED_SIZE, 265, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, 265, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(panel1Layout.createSequentialGroup()
.addGap(67, 67, 67)
.addComponent(label2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addComponent(list2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGap(0, 8, Short.MAX_VALUE))
);
panel1Layout.setVerticalGroup(
panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel1Layout.createSequentialGroup()
.addGroup(panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, panel1Layout.createSequentialGroup()
.addComponent(ekle, javax.swing.GroupLayout.PREFERRED_SIZE, 75, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(sil, javax.swing.GroupLayout.PREFERRED_SIZE, 67, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED))
.addGroup(panel1Layout.createSequentialGroup()
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(list1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(label2, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(2, 2, 2)))
.addGroup(panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addGroup(panel1Layout.createSequentialGroup()
.addComponent(ara, javax.swing.GroupLayout.PREFERRED_SIZE, 51, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(iade, javax.swing.GroupLayout.PREFERRED_SIZE, 63, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(list2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(panel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(panel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}
private void ekleActionPerformed(java.awt.event.ActionEvent evt) {
panel1.removeAll();
getToWork=PanelFactory.getWork("add");
this.add(getToWork.builder());
this.repaint();
this.validate();
}
public static void main(String args[]) {
instance=LibrarySystemInterface.getInstance();
}
public static LibrarySystemInterface getInstance() {
if (instance==null)
return instance=new LibrarySystemInterface();
else return instance;
}
private java.awt.Button ara;
private java.awt.Button ekle;
private java.awt.Button iade;
private java.awt.Label label1;
private java.awt.Label label2;
private java.awt.List list1;
private java.awt.List list2;
private java.awt.Panel panel1;
private java.awt.Button sil;
// End of variables declaration
#Override
public Panel builder() {
this.initComponents();
updateNList();
return panel1;
}
public void updateNList(){
list1.removeAll();
ArrayList<Collection> item=new ArrayList<Collection>();
kutuphane=library.getInstance();
forCode= kutuphane.iterator();
while(!forCode.hasNext()){
collection=(Collection) forCode.next();
String itemStr=collection.type + ", " + collection.name + ", " + collection.auther + ", " + collection.date
+ ", " + collection.code;
list2.add(itemStr);
}
}
}
Add book section
public class EkleInterface extends javax.swing.JFrame implements PanelWorker{
private FileReaderWriter writer;
private LibraryIterator forCode ;
private Library kutuphane;
private Collection collection;
private int count=1;
private PanelWorker getToWork;
private Library library = null;
public EkleInterface() {
initComponents();
writer=new FileReaderWriter("prevent");
kutuphane=Library.getInstance();
private void initComponents() {
panel2 = new java.awt.Panel();
label1 = new java.awt.Label();
textField1 = new java.awt.TextField();
label2 = new java.awt.Label();
textField2 = new java.awt.TextField();
label3 = new java.awt.Label();
textField3 = new java.awt.TextField();
label4 = new java.awt.Label();
textField4 = new java.awt.TextField();
ekle = new java.awt.Button();
Menu = new java.awt.Button();
label5 = new java.awt.Label();
list2 = new java.awt.List();
label6 = new java.awt.Label();
list1 = new java.awt.List();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
panel2.setName("");
label1.setText("Tur:");
textField1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
textField1ActionPerformed(evt);
}
});
label2.setText("Ismi");
textField2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
textField2ActionPerformed(evt);
}
});
label3.setText("Yazari");
textField3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
textField3ActionPerformed(evt);
}
});
label4.setText("Yayınlanma Tarihi");
textField4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
textField4ActionPerformed(evt);
}
});
ekle.setLabel("Ekle");
ekle.setName(""); // NOI18N
ekle.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
ekleActionPerformed(evt);
}
});
Menu.setLabel("Menu");
Menu.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
MenuActionPerformed(evt);
}
});
label5.setText("Butun Kitaplarin Listesi");
label6.setText("Odunc Verilcek Kitaplarin Listesi");
list1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
list1ActionPerformed(evt);
}
});
javax.swing.GroupLayout panel2Layout = new javax.swing.GroupLayout(panel2);
panel2.setLayout(panel2Layout);
panel2Layout.setHorizontalGroup(
panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel2Layout.createSequentialGroup()
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, 76, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(53, 53, 53)
.addComponent(textField1, javax.swing.GroupLayout.PREFERRED_SIZE, 117, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(label2, javax.swing.GroupLayout.PREFERRED_SIZE, 76, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(textField2, javax.swing.GroupLayout.PREFERRED_SIZE, 117, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(label3, javax.swing.GroupLayout.PREFERRED_SIZE, 76, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(textField3, javax.swing.GroupLayout.PREFERRED_SIZE, 117, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(label5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 0, Short.MAX_VALUE))
.addComponent(list2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
.addGroup(panel2Layout.createSequentialGroup()
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(panel2Layout.createSequentialGroup()
.addContainerGap()
.addComponent(ekle, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(6, 6, 6)
.addComponent(Menu, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(label4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(27, 27, 27)
.addComponent(textField4, javax.swing.GroupLayout.PREFERRED_SIZE, 118, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(label6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
.addComponent(list1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
);
panel2Layout.setVerticalGroup(
panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel2Layout.createSequentialGroup()
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, 31, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(label5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField1, javax.swing.GroupLayout.PREFERRED_SIZE, 24, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(panel2Layout.createSequentialGroup()
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(label2, javax.swing.GroupLayout.PREFERRED_SIZE, 37, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField2, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(textField3, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(label3, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(list2, javax.swing.GroupLayout.PREFERRED_SIZE, 88, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(10, 10, 10)))
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(panel2Layout.createSequentialGroup()
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(label4, javax.swing.GroupLayout.DEFAULT_SIZE, 40, Short.MAX_VALUE)
.addComponent(textField4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(ekle, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(Menu, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(47, Short.MAX_VALUE))
.addGroup(panel2Layout.createSequentialGroup()
.addComponent(label6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(list1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(panel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 14, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(panel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}
private void ekleActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String type=textField1.getText();
String name=textField2.getText();
String date=textField4.getText();
String auther=textField3.getText();
forCode= kutuphane.iterator();
while(!forCode.hasNext()){
collection=(Collection) forCode.next();
count=collection.code+1;
}
String url = "jdbc:mysql://127.0.0.1:3306/";
String dbName = "kutuphane";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "123456";
try {
Class.forName(driver).newInstance();
Connection conn = DriverManager.getConnection(url+dbName,userName,password);
Statement st = conn.createStatement();
String query = " insert into kitaplar (tur,yazar,tarih, ismi)"
+ " values ( ?, ?, ?, ?)";
PreparedStatement preparedStmt = conn.prepareStatement(query);
preparedStmt.setString (1, type);
preparedStmt.setString (2, auther);
preparedStmt.setString (3, date);
preparedStmt.setString(4, name);
preparedStmt.execute();
conn.close();
}
catch (ClassNotFoundException k) {
} catch (InstantiationException k) {
} catch (IllegalAccessException k) {
} catch (SQLException k) {
}
kutuphane.addAggregate(collection=new Collection(type,name,auther,
date,count));
updateNList();
}
private void MenuActionPerformed(java.awt.event.ActionEvent evt) {
panel2.removeAll();
getToWork=PanelFactory.getWork("menu");
this.add(getToWork.builder());
this.repaint();
this.validate();
}
private java.awt.Button Menu;
private java.awt.Button ekle;
private java.awt.Label label1;
private java.awt.Label label2;
private java.awt.Label label3;
private java.awt.Label label4;
private java.awt.Label label5;
private java.awt.Label label6;
private java.awt.List list1;
private java.awt.List list2;
private java.awt.Panel panel2;
private java.awt.TextField textField1;
private java.awt.TextField textField2;
private java.awt.TextField textField3;
private java.awt.TextField textField4;
public Panel builder() {
initComponents();
updateNList();
return panel2;
}
public void updateNList(){
list1.removeAll();
ArrayList<Collection> item=new ArrayList<Collection>();
kutuphane=library.getInstance();
forCode= kutuphane.iterator();
while(!forCode.hasNext()){
collection=(Collection) forCode.next();
String itemStr=collection.type + ", " + collection.name + ", " + collection.auther + ", " + collection.date
+ ", " + collection.code;
list2.add(itemStr);
}
}
}
Interface:
public interface PanelWorker {
public Panel builder();
}
public class PanelFactory {
public static PanelWorker getWork(String whereTo){
if(whereTo.equals("add")){
return new EkleInterface();
}
else if (whereTo.equals("delete")){
return new SilInterci();
}
else if (whereTo.equals("menu"))
return new LibrarySystemInterface();
else if(whereTo.equals("search"))
return new AraInterface();
else if(whereTo.equals("rentFinish"))
return new IadeInterface();
return null;
}
}

JTextfield Focus between two JInternalFrame

In my application I have 3 classes that extends JInternalframe. One is MainFrame. Suppose Mainframe has four JTextFields. TF1, TF2, TF3, TF4. When the MainFrame is opened TF1 got focus by default.
Now user will press enter and go to TF2. In the next step depending on a condition Another JInternalFrame SubFrame_1 or SubFrame_2 will get opened as a floating window.
SubFrame_1 has four different TextFields. TF5, TF6, TF7, TF8. Again TF5 got focus by default. Some calculations will be done here and when user presses enter in TF8 SubFrame_1 will be disposed. And the MainFrame should regain focus in TF3. The same condition may be applied to SubFrame_2. But when SubFrame_1 is disposed TF3 never gain focus. More horrible thing is that sometimes the MainFrame does not get focused when the SubFrame is disposed. How can I get rid of this issue? I've tried all sort of function requestFocusInWindow(), requestFocus(), grabFocus() etc. Please help.

Here is my small example:
public class Form1 extends javax.swing.JFrame {
/**
* Creates new form Form1
*/
public Form1() {
initComponents();
this.jInternalFrame2.setVisible(false);
this.jInternalFrame3.setVisible(false);
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jInternalFrame1 = new javax.swing.JInternalFrame();
jButton1 = new javax.swing.JButton();
jTextField1 = new javax.swing.JTextField();
jTextField2 = new javax.swing.JTextField();
jTextField3 = new javax.swing.JTextField();
jInternalFrame2 = new javax.swing.JInternalFrame();
jInternalFrame3 = new javax.swing.JInternalFrame();
jTextField4 = new javax.swing.JTextField();
jTextField5 = new javax.swing.JTextField();
jButton2 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jInternalFrame1.setTitle("JIF1");
jInternalFrame1.setVisible(true);
jButton1.setText("Focus In JIF 2");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jTextField1.setText("jTextField1");
jTextField2.setText("jTextField1");
jTextField3.setText("jTextField1");
javax.swing.GroupLayout jInternalFrame1Layout = new javax.swing.GroupLayout(jInternalFrame1.getContentPane());
jInternalFrame1.getContentPane().setLayout(jInternalFrame1Layout);
jInternalFrame1Layout.setHorizontalGroup(
jInternalFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jInternalFrame1Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jInternalFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, 179, Short.MAX_VALUE)
.addGroup(jInternalFrame1Layout.createSequentialGroup()
.addGroup(jInternalFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(0, 0, Short.MAX_VALUE)))
.addContainerGap())
);
jInternalFrame1Layout.setVerticalGroup(
jInternalFrame1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jInternalFrame1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 109, Short.MAX_VALUE)
.addComponent(jButton1)
.addContainerGap())
);
jInternalFrame2.setVisible(true);
javax.swing.GroupLayout jInternalFrame2Layout = new javax.swing.GroupLayout(jInternalFrame2.getContentPane());
jInternalFrame2.getContentPane().setLayout(jInternalFrame2Layout);
jInternalFrame2Layout.setHorizontalGroup(
jInternalFrame2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 0, Short.MAX_VALUE)
);
jInternalFrame2Layout.setVerticalGroup(
jInternalFrame2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 128, Short.MAX_VALUE)
);
jInternalFrame3.setTitle("JIF2");
jInternalFrame3.setVisible(true);
jTextField4.setText("jTextField4");
jTextField5.setText("jTextField5");
jButton2.setText("Focus in JIF 1");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
javax.swing.GroupLayout jInternalFrame3Layout = new javax.swing.GroupLayout(jInternalFrame3.getContentPane());
jInternalFrame3.getContentPane().setLayout(jInternalFrame3Layout);
jInternalFrame3Layout.setHorizontalGroup(
jInternalFrame3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jInternalFrame3Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jInternalFrame3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addComponent(jButton2, javax.swing.GroupLayout.DEFAULT_SIZE, 284, Short.MAX_VALUE)
);
jInternalFrame3Layout.setVerticalGroup(
jInternalFrame3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jInternalFrame3Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton2)
.addContainerGap())
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jInternalFrame1)
.addComponent(jInternalFrame2))
.addGap(18, 18, 18)
.addComponent(jInternalFrame3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(121, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jInternalFrame3)
.addComponent(jInternalFrame1))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jInternalFrame2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
this.jInternalFrame3.setVisible(true);
this.jTextField4.requestFocus();
this.jInternalFrame1.setVisible(false);
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
this.jInternalFrame1.setVisible(true);
this.jTextField3.requestFocus();
this.jInternalFrame3.setVisible(false);
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(Form1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Form1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Form1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Form1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Form1().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JInternalFrame jInternalFrame1;
private javax.swing.JInternalFrame jInternalFrame2;
private javax.swing.JInternalFrame jInternalFrame3;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
private javax.swing.JTextField jTextField4;
private javax.swing.JTextField jTextField5;
// End of variables declaration
}

Set a JFrame to appear in center not working?

I am developing a swing application and I created a log in form. I set it appear in center of the screen but not working :( I tried two ways (1) and (2) but both not working.
I cant understand why. Because both of the solutions were in this site.
My Code:
public class LoginForm extends javax.swing.JFrame {
public LoginForm() {
/*Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
this.setLocation(dim.width/2-this.getSize().width/2, dim.height/2- this.getSize().height/2);*/ // ----> (1)
setLocationRelativeTo(null); // ----> (2)
initComponents();
}
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JPanel jPanel1;
private javax.swing.JPasswordField jPasswordField1;
private javax.swing.JTextField jTextField1;
private java.awt.Label label1;
private void initComponents() {
setUndecorated(true);
jPanel1 = new javax.swing.JPanel();
jTextField1 = new RoundJTextField(20);
jPasswordField1 = new RoundJPasswordField(20);
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
label1 = new java.awt.Label();
jButton2 = new javax.swing.JButton();
jButton1 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setBackground(new java.awt.Color(255, 255, 255));
setBounds(new java.awt.Rectangle(5, 0, 0, 0));
setName("LogInFrame"); // NOI18N
setResizable(false);
jPanel1.setBackground(new java.awt.Color(255, 255, 255));
jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jLabel1.setFont(new java.awt.Font("Segoe UI", 0, 18)); // NOI18N
jLabel1.setText("Username");
jLabel2.setFont(new java.awt.Font("Segoe UI", 0, 18)); // NOI18N
jLabel2.setText("Password");
label1.setFont(new java.awt.Font("SansSerif", 1, 18)); // NOI18N
label1.setText("UAC Login");
jButton2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/images/windows_close_program.png"))); // NOI18N
jButton2.setActionCommand("loginExit");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
jButton1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/images/go.JPG"))); // NOI18N
jButton1.setActionCommand("LoginButton");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jButton3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/images/join.JPG"))); // NOI18N
jButton3.setText("jButton3");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(60, 60, 60)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 104, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jPasswordField1, javax.swing.GroupLayout.DEFAULT_SIZE, 198, Short.MAX_VALUE)
.addComponent(jTextField1)
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(21, 21, 21)
.addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 262, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 55, Short.MAX_VALUE)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 81, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(22, 22, 22))))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(20, 20, 20)
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(2, 2, 2)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 207, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(46, Short.MAX_VALUE))
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(57, 57, 57)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 28, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(40, 40, 40)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(jPasswordField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 24, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(34, 34, 34))))
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 0, 0))
);
pack();
}// </editor-fold>
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
System.exit(0);
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
this.setVisible(false);
this.dispose();
new RegistrationForm();
}
public static void main(String args[]) {
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Synth".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(LoginForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(LoginForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(LoginForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(LoginForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new LoginForm().setVisible(true);
}
});
}
}

Your order is off:
Add components first.
Then pack()
Then setLocationRelativeTo(null) -- you're doing this too early
Then setVisible(true)

setLocationRelativeTo will use the frames current size to determine how best to achieve the desired results. Seen as you've not actually added anything to the frame AND you've not set it's size, the only value it has to go on is 0x0 (size).
Try move setLocationRelativeTo after initComponents, but adding pack before you call it, for example...
public LoginForm() {
/*Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
this.setLocation(dim.width/2-this.getSize().width/2, dim.height/2- this.getSize().height/2);*/ // ----> (1)
initComponents();
pack();
setLocationRelativeTo(null); // ----> (2)
}

If you are using **netBeanIDE 7.**3. you may do this as.
->in design ,right click -> select properties and
and checked generate center.it will solve your problem without looking into code.
Hope it may help u.