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Java Swing jLabel java.lang.NullPointerException [duplicate]

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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()

JApplet open new window when click on jButton3

this is my Applet so far, i can´t figure out how to open a new window (JFrame), when i click on "Register" JButton, i want to open a new window "Register Form Window" is to register all users (User Name, User Password, Age, etc).
LogIn.java
package intranetmailingsystem;
import java.lang.reflect.InvocationTargetException;
import javax.swing.JFrame;
public class LogIn extends javax.swing.JApplet{
#Override
public void init() {
try {
java.awt.EventQueue.invokeAndWait(this::initComponents);
} catch (InterruptedException | InvocationTargetException ex) {
}
}
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
jTextField2 = new javax.swing.JTextField();
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
jLabel1.setText("Intranet Mailing System");
jLabel2.setText("User name");
jLabel3.setText("Password");
jTextField2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField2ActionPerformed(evt);
}
});
jButton1.setText("LogIn");
jButton2.setText("Clear");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
jButton3.setText("Register");
jButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton3ActionPerformed(evt);
}
});
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(layout.createSequentialGroup()
.addGap(35, 35, 35)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, 75, Short.MAX_VALUE)
.addComponent(jLabel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGap(36, 36, 36)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jTextField1)
.addComponent(jTextField2, javax.swing.GroupLayout.DEFAULT_SIZE, 128, Short.MAX_VALUE)))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addGroup(layout.createSequentialGroup()
.addGap(53, 53, 53)
.addComponent(jButton1)
.addGap(48, 48, 48)
.addComponent(jButton2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton3))
.addGroup(layout.createSequentialGroup()
.addGap(68, 68, 68)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 283, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addContainerGap(49, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(22, 22, 22)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(38, 38, 38)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(jTextField1, 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(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 64, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton1)
.addComponent(jButton2)
.addComponent(jButton3))
.addGap(65, 65, 65))
);
}// </editor-fold>
private void jTextField2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
// need to add some code here !
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
{
jTextField1.setText("");
jTextField2.setText("");
}
}
// Variables declaration - do not modify
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.JLabel jLabel3;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
// End of variables declaration
private void dispose() {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
}
InternetMailingSystem.java :
package intranetmailingsystem;
public class IntranetMailingSystem
{
public static void main(String[] args)
{
// TODO code application logic here
}
}
Please check this:
Image

You have to create another window. So if you create another JFrame class call Register you would add this in your code.
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
Register menu = new Register();
menu.setVisible(true);
}

Output Changing from JFrame to Java Result [closed]

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 7 years ago.
Improve this question
I have been running a JFrame in NetBeans to test it and all of a sudden the output changed from a display of the JFrame to:
Java Result: -1073740940
I do not know what caused this as I did not change anything in the run method and it is effecting all of my JFrame programs. Does anybody have any idea what is causing this? Is it a glitch in the program or did I accidentally toggled a setting NetBeans has that I'm not aware of?
UPDATE:
Here is the code to the program as requested by someone, but as I stated before it affects multiple projects that use a JFrame
/*
* 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.
*/
package imeannumbers;
import javax.swing.BorderFactory;
import javax.swing.border.TitledBorder;
/**
*
* #author Kanto Ruki
*/
public class Main extends javax.swing.JFrame {
/**
* Creates new form Main
*/
boolean decimalUsed = false;
public Main() {
initComponents();
}
/**
* 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() {
tabGrouping = new javax.swing.JTabbedPane();
tabNumPad = new javax.swing.JPanel();
txtBox = new javax.swing.JTextField();
btnOne = new javax.swing.JButton();
btnTwo = new javax.swing.JButton();
btnThree = new javax.swing.JButton();
btnFour = new javax.swing.JButton();
btnFive = new javax.swing.JButton();
btnSix = new javax.swing.JButton();
btnSeven = new javax.swing.JButton();
btnEight = new javax.swing.JButton();
btnNine = new javax.swing.JButton();
btnDecimal = new javax.swing.JButton();
btnZero = new javax.swing.JButton();
btnEnter = new javax.swing.JButton();
tabAchievements = new javax.swing.JScrollPane();
jPanel1 = new javax.swing.JPanel();
lbl00 = new javax.swing.JLabel();
lbl01 = new javax.swing.JLabel();
lbl03 = new javax.swing.JLabel();
lbl05 = new javax.swing.JLabel();
lbl07 = new javax.swing.JLabel();
lbl13 = new javax.swing.JLabel();
jPanel3 = new javax.swing.JPanel();
jPanel4 = new javax.swing.JPanel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("I Mean Numbers");
txtBox.setEditable(false);
txtBox.setHorizontalAlignment(javax.swing.JTextField.RIGHT);
txtBox.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.LOWERED));
btnOne.setText("1");
btnOne.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnOneActionPerformed(evt);
}
});
btnTwo.setText("2");
btnTwo.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnTwoActionPerformed(evt);
}
});
btnThree.setText("3");
btnThree.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnThreeActionPerformed(evt);
}
});
btnFour.setText("4");
btnFour.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnFourActionPerformed(evt);
}
});
btnFive.setText("5");
btnFive.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnFiveActionPerformed(evt);
}
});
btnSix.setText("6");
btnSix.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnSixActionPerformed(evt);
}
});
btnSeven.setText("7");
btnSeven.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnSevenActionPerformed(evt);
}
});
btnEight.setText("8");
btnEight.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnEightActionPerformed(evt);
}
});
btnNine.setText("9");
btnNine.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnNineActionPerformed(evt);
}
});
btnDecimal.setText(".");
btnDecimal.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnDecimalActionPerformed(evt);
}
});
btnZero.setText("0");
btnZero.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnZeroActionPerformed(evt);
}
});
btnEnter.setText("Enter");
btnEnter.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnEnterActionPerformed(evt);
}
});
javax.swing.GroupLayout tabNumPadLayout = new javax.swing.GroupLayout(tabNumPad);
tabNumPad.setLayout(tabNumPadLayout);
tabNumPadLayout.setHorizontalGroup(
tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(tabNumPadLayout.createSequentialGroup()
.addGap(82, 82, 82)
.addGroup(tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(tabNumPadLayout.createSequentialGroup()
.addComponent(btnDecimal, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnZero, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnEnter, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGroup(tabNumPadLayout.createSequentialGroup()
.addComponent(btnSeven, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnEight, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnNine, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(tabNumPadLayout.createSequentialGroup()
.addComponent(btnFour, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnFive, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnSix, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(tabNumPadLayout.createSequentialGroup()
.addComponent(btnOne, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnTwo, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnThree, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(txtBox))
.addContainerGap(77, Short.MAX_VALUE))
);
tabNumPadLayout.setVerticalGroup(
tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(tabNumPadLayout.createSequentialGroup()
.addGap(20, 20, 20)
.addComponent(txtBox, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addGroup(tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btnOne, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnTwo, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnThree, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btnFour, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnFive, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnSix, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btnSeven, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnEight, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnNine, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(tabNumPadLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btnDecimal, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnZero, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnEnter, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
tabGrouping.addTab("NumPad", tabNumPad);
lbl00.setText("??");
lbl00.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "?????", javax.swing.border.TitledBorder.RIGHT, javax.swing.border.TitledBorder.BOTTOM));
lbl01.setText("??");
lbl01.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "?????", javax.swing.border.TitledBorder.RIGHT, javax.swing.border.TitledBorder.BOTTOM));
lbl03.setText("??");
lbl03.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "?????", javax.swing.border.TitledBorder.RIGHT, javax.swing.border.TitledBorder.BOTTOM));
lbl05.setText("??");
lbl05.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "?????", javax.swing.border.TitledBorder.RIGHT, javax.swing.border.TitledBorder.BOTTOM));
lbl07.setText("??");
lbl07.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "?????", javax.swing.border.TitledBorder.RIGHT, javax.swing.border.TitledBorder.BOTTOM));
lbl13.setText("??");
lbl13.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "?????", javax.swing.border.TitledBorder.RIGHT, javax.swing.border.TitledBorder.BOTTOM));
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(34, 34, 34)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(lbl05, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lbl07, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lbl13, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(lbl00, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lbl01, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lbl03, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(42, Short.MAX_VALUE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(lbl03)
.addComponent(lbl01)
.addComponent(lbl00))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.CENTER)
.addComponent(lbl05)
.addComponent(lbl07)
.addComponent(lbl13))
.addContainerGap(141, Short.MAX_VALUE))
);
tabAchievements.setViewportView(jPanel1);
tabGrouping.addTab("Achievements", tabAchievements);
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 390, Short.MAX_VALUE)
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 232, Short.MAX_VALUE)
);
tabGrouping.addTab("How To Play", jPanel3);
javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
jPanel4.setLayout(jPanel4Layout);
jPanel4Layout.setHorizontalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 390, Short.MAX_VALUE)
);
jPanel4Layout.setVerticalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 232, Short.MAX_VALUE)
);
tabGrouping.addTab("About", jPanel4);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(tabGrouping)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(tabGrouping)
);
pack();
setLocationRelativeTo(null);
}// </editor-fold>
private void btnOneActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "1");
}
private void btnTwoActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "2");
}
private void btnThreeActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "3");
}
private void btnFourActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "4");
}
private void btnFiveActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "5");
}
private void btnSixActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "6");
}
private void btnSevenActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "7");
}
private void btnEightActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "8");
}
private void btnNineActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "9");
}
private void btnDecimalActionPerformed(java.awt.event.ActionEvent evt) {
if (!decimalUsed) {
txtBox.setText(txtBox.getText() + ".");
decimalUsed = true;
}
}
private void btnZeroActionPerformed(java.awt.event.ActionEvent evt) {
txtBox.setText(txtBox.getText() + "0");
}
private void btnEnterActionPerformed(java.awt.event.ActionEvent evt) {
String check = txtBox.getText();
TitledBorder title = BorderFactory.createTitledBorder("title");
title.setTitleJustification(TitledBorder.RIGHT);
title.setTitlePosition(TitledBorder.BOTTOM);
switch (check) {
case "00":
title.setTitle("The Beginning...");
lbl00.setBorder(title);
lbl00.setText("00");
break;
case "01":
title.setTitle("Your the First");
lbl01.setBorder(title);
lbl01.setText("01");
break;
default:
break;
}
decimalUsed = false;
txtBox.setText("");
}
/**
* #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(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Main.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 Main().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton btnDecimal;
private javax.swing.JButton btnEight;
private javax.swing.JButton btnEnter;
private javax.swing.JButton btnFive;
private javax.swing.JButton btnFour;
private javax.swing.JButton btnNine;
private javax.swing.JButton btnOne;
private javax.swing.JButton btnSeven;
private javax.swing.JButton btnSix;
private javax.swing.JButton btnThree;
private javax.swing.JButton btnTwo;
private javax.swing.JButton btnZero;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel3;
private javax.swing.JPanel jPanel4;
private javax.swing.JLabel lbl00;
private javax.swing.JLabel lbl01;
private javax.swing.JLabel lbl03;
private javax.swing.JLabel lbl05;
private javax.swing.JLabel lbl07;
private javax.swing.JLabel lbl13;
private javax.swing.JScrollPane tabAchievements;
private javax.swing.JTabbedPane tabGrouping;
private javax.swing.JPanel tabNumPad;
private javax.swing.JTextField txtBox;
// End of variables declaration
}
UPDATE2:
Thanks to #Willshackleford, I found that the problem is occurring in the main execution in the EventQueue
public static void invokeLater(Runnable runnable) {
Toolkit.getEventQueue().postEvent(
new InvocationEvent(Toolkit.getDefaultToolkit(), runnable));
}
With the Error Message Variable information not available, source compiled without -g option

You may have toggled a setting. If you select your project, and choose Properties in the pop-up menu and then select the category run. There are a couple of properties that would mess things up. The main class could be changed to a class other than your JFrame class. Setting the platform to a JDK version you don't have installed or have a broken installation for etc.
Probably the best way to debug would be to select the project and choose Debug -> Step Into or press F7 from them menu. This will start your program but immediately pause it so you can step through it one line at a time by pressing F7 (Step Into) or F8 (Step Over) for each line. If it starts stepping into the wrong class you will no you need to fix the main class property. If it starts ok but exits early you will want to look carefully at the last line before it exits.

I have an error with my if statement [duplicate]

This question already exists:
If statement for jframe main method doesn't work [duplicate]
Closed 7 years ago.
I'm new to java, I'm trying to select shape using jframe and then display the area using console output, I tried using it as follow, but it's giving me an error. Not sure how to do an if statement, it says non static variable can't be referenced from static context. How to fix my code?
Thank you in advance
public class design extends javax.swing.JFrame {
int type;
int xtl, ytl, xtr, ytr, xbl, ybl,xbr, ybr;
/**
* Creates new form design
*/
public design() {
initComponents();
}
/**
* 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() {
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jButton4 = new javax.swing.JButton();
jButton5 = new javax.swing.JButton();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jLabel4 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
jLabel6 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
jTextField2 = new javax.swing.JTextField();
jTextField3 = new javax.swing.JTextField();
jTextField4 = new javax.swing.JTextField();
jTextField5 = new javax.swing.JTextField();
jTextField6 = new javax.swing.JTextField();
jTextField7 = new javax.swing.JTextField();
jTextField8 = new javax.swing.JTextField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jButton1.setText("Quadrilateral");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jButton2.setText("Rectangle");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
jButton3.setText("Parallelogram");
jButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton3ActionPerformed(evt);
}
});
jButton4.setText("Square");
jButton4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton4ActionPerformed(evt);
}
});
jButton5.setText("Trapezoid");
jButton5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton5ActionPerformed(evt);
}
});
jLabel1.setText("X:");
jLabel2.setText("Y:");
jLabel3.setText("Top left point");
jLabel4.setText("Top right point");
jLabel5.setText("Bottom left point");
jLabel6.setText("Bottom right point");
jTextField1.setText(" ");
jTextField1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField1ActionPerformed(evt);
}
});
jTextField2.setText(" ");
jTextField2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField2ActionPerformed(evt);
}
});
jTextField3.setText(" ");
jTextField3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField3ActionPerformed(evt);
}
});
jTextField4.setText(" ");
jTextField4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField4ActionPerformed(evt);
}
});
jTextField5.setText(" ");
jTextField5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField5ActionPerformed(evt);
}
});
jTextField6.setText(" ");
jTextField6.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField6ActionPerformed(evt);
}
});
jTextField7.setText(" ");
jTextField7.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField7ActionPerformed(evt);
}
});
jTextField8.setText(" ");
jTextField8.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField8ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(24, 24, 24)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addGap(47, 47, 47)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(90, 90, 90)
.addComponent(jButton4)
.addGap(142, 142, 142)
.addComponent(jButton5)
.addGap(0, 0, Short.MAX_VALUE))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(0, 40, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jTextField1)
.addComponent(jTextField5))
.addComponent(jLabel3))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(39, 39, 39)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(58, 58, 58)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jTextField7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(67, 67, 67)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGap(44, 44, 44)
.addComponent(jLabel4)
.addGap(27, 27, 27)
.addComponent(jLabel5)
.addGap(32, 32, 32)
.addComponent(jLabel6)))
.addGap(137, 137, 137))))
.addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel2)
.addComponent(jLabel1))
.addContainerGap())
.addGroup(layout.createSequentialGroup()
.addComponent(jButton1)
.addGap(148, 148, 148)
.addComponent(jButton3)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton2)
.addGap(75, 75, 75))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(20, 20, 20)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton1)
.addComponent(jButton3)
.addComponent(jButton2))
.addGap(26, 26, 26)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton4)
.addComponent(jButton5))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 73, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3)
.addComponent(jLabel4)
.addComponent(jLabel5)
.addComponent(jLabel6))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.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)
.addComponent(jTextField4, 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(jTextField8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2)
.addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(43, 43, 43))
);
pack();
}// </editor-fold>
private void jTextField7ActionPerformed(java.awt.event.ActionEvent evt) {
ybl = Integer.parseInt(jTextField7.getText()); }
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
type =1;
// TODO add your handling code here:
}
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
type =2;
// TODO add your handling code here:
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
type =3;
}
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
type =4;
// TODO add your handling code here:
}
private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {
type =5;
// TODO add your handling code here:
}
private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {
xtl = Integer.parseInt(jTextField1.getText());
}
private void jTextField5ActionPerformed(java.awt.event.ActionEvent evt) {
ytl = Integer.parseInt(jTextField5.getText());
}
private void jTextField3ActionPerformed(java.awt.event.ActionEvent evt) {
xtr = Integer.parseInt(jTextField3.getText());
}
private void jTextField6ActionPerformed(java.awt.event.ActionEvent evt) {
ytr = Integer.parseInt(jTextField6.getText());
}
private void jTextField4ActionPerformed(java.awt.event.ActionEvent evt) {
xbl = Integer.parseInt(jTextField4.getText());
}
private void jTextField2ActionPerformed(java.awt.event.ActionEvent evt) {
xbr = Integer.parseInt(jTextField2.getText());
}
private void jTextField8ActionPerformed(java.awt.event.ActionEvent evt) {
ybr = Integer.parseInt(jTextField8.getText());
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
if (type==1){
System.out.println("Qoordinates of Quadrilateral are");
}
if (type==2){
System.out.println("Text2");
}
/* 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(design.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(design.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(design.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(design.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() {
System.out.println("Hello World");
new design().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JButton jButton4;
private javax.swing.JButton jButton5;
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.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
private javax.swing.JTextField jTextField4;
private javax.swing.JTextField jTextField5;
private javax.swing.JTextField jTextField6;
private javax.swing.JTextField jTextField7;
private javax.swing.JTextField jTextField8;
// End of variables declaration
}

(Style nit: your design class should be named Design.)
In your main method, you hadn't created a new Design object yet. You can only access type for a Design instance.

NetBeans Java Project Won't Display GUI Window Despite No Error

I am trying to build a java project using Netbeans IDE 7.1.
I somehow can't see or view the GUI window that I have created.
Please kindly advise.
In my class:
package rmiSimpleCalc;
public class RMISimpleCalculatorMain {
public static void main(String[] args) {
MainCalculator calc = new MainCalculator();
calc.setVisible(true);
}
}
the MainCalculator is the GUI window I would like to run. It somehow wont't display.
There is NO error message in my console tough..
Here is the MainCalculator code:
package rmiSimpleCalc;
import java.rmi.*;
public class MainCalculator extends javax.swing.JPanel {
public MainCalculator() {
initComponents();
ComboBoxOperator.addItem("+");
ComboBoxOperator.addItem("-");
ComboBoxOperator.addItem("/");
ComboBoxOperator.addItem("*");
}
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
txtFirstDigit = new javax.swing.JTextField();
txtSecondDigit = new javax.swing.JTextField();
btnCalculate = new javax.swing.JButton();
lblFirstDigit = new javax.swing.JLabel();
lblSecondDigit = new javax.swing.JLabel();
ComboBoxOperator = new javax.swing.JComboBox();
lblOperator = new javax.swing.JLabel();
lblResult = new javax.swing.JLabel();
lblHeader = new javax.swing.JLabel();
btnConfigureServer = new javax.swing.JButton();
txtResult = new javax.swing.JTextField();
btnCalculate.setText("Calculate");
btnCalculate.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnCalculateActionPerformed(evt);
}
});
lblFirstDigit.setText("First Digit");
lblSecondDigit.setText("Second Digit");
ComboBoxOperator.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
lblOperator.setText("Operator");
lblResult.setText("Result");
lblHeader.setText("RMI Simple Calculator");
btnConfigureServer.setText("Configure Server");
btnConfigureServer.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnConfigureServerActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.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)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(lblFirstDigit, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(lblSecondDigit, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(lblOperator, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(lblResult, javax.swing.GroupLayout.Alignment.TRAILING))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(lblHeader)
.addGroup(layout.createSequentialGroup()
.addComponent(ComboBoxOperator, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(btnCalculate))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(txtSecondDigit)
.addComponent(txtFirstDigit, javax.swing.GroupLayout.PREFERRED_SIZE, 128, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(txtResult, javax.swing.GroupLayout.PREFERRED_SIZE, 125, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnConfigureServer)))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(12, 12, 12)
.addComponent(lblHeader)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(txtFirstDigit, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(lblFirstDigit))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(txtSecondDigit, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(lblSecondDigit))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(ComboBoxOperator, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(lblOperator)
.addComponent(btnCalculate))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(lblResult)
.addComponent(txtResult, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(btnConfigureServer)
.addContainerGap(24, Short.MAX_VALUE))
);
}
private void btnConfigureServerActionPerformed(java.awt.event.ActionEvent evt) {
}
private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {
double firstdigit;
double seconddigit;
String operator;
firstdigit = Double.valueOf(txtFirstDigit.getText());
seconddigit = Double.valueOf(txtSecondDigit.getText());
operator = ComboBoxOperator.getSelectedItem().toString();
try
{
CoreInterface coreobj = (CoreInterface) Naming.lookup("localhost/Core");
double result = (coreobj.calc(firstdigit,seconddigit,operator));
txtResult.setText(Double.toString(result));
}
catch(Exception e)
{
txtResult.setText("e");
}
}
private javax.swing.JComboBox ComboBoxOperator;
private javax.swing.JButton btnCalculate;
private javax.swing.JButton btnConfigureServer;
private javax.swing.JLabel lblFirstDigit;
private javax.swing.JLabel lblHeader;
private javax.swing.JLabel lblOperator;
private javax.swing.JLabel lblResult;
private javax.swing.JLabel lblSecondDigit;
private javax.swing.JTextField txtFirstDigit;
private javax.swing.JTextField txtResult;
private javax.swing.JTextField txtSecondDigit;
// End of variables declaration
}
Any advise is appreciated.

The MainCalculator class is a JPanel. A JPanel can't just be displayed like that, it has to be part of a Window. Add it to a JFrame and call setVisible(true) on the JFrame.
Also, #npinti's advice is very good: execute GUI-related code in the EDT thread.

The issue is most likely in this section:
public static void main(String[] args) {
MainCalculator calc = new MainCalculator();
calc.setVisible(true);
}
You need to make any GUI related tasks within the Event Dispatcher Thread (EDT).
Try something like so:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
MainCalculator calc = new MainCalculator();
calc.setVisible(true);
}
});
}