Develop Reference

Storing JTextField input in a String variable

So I want to store a string value in a variable, the value is given through a JTextField and after a confirm button is clicked, I want it to store what's written in the text field in a string variable.
This is the relevant part of the code:
public class Window {
private JButton confirm;
private JTextField textfield;
private JLabel label;
public void drawWindow() {
JFrame window = new JFrame("CountryQuiz");
ClickChecker click = new ClickChecker();
JPanel panel = new JPanel();
panel.setBounds(40, 80, 200, 200);
panel.setBackground(Color.green);
JTextField t1 = new JTextField("Enter country...");
t1.setBounds(50, 100, 200, 30);
window.add(t1);
JButton confirm = new JButton("Confirm");
confirm.setBounds(50, 50, 95, 30);
confirm.addActionListener(click);
window.add(confirm);
window.setSize(400, 400);
window.setLayout(null);
window.setVisible(true);
window.add(panel);
}
private class ClickChecker implements ActionListener {
public void actionPerformed(ActionEvent e) {
String answer = textfield.getText();
System.out.println(answer);
}
}
}
Results in the following error:
Cannot invoke "javax.swing.JTextField.getText()" because "this.this$0.textfield" is null

Your textfield variable is only declared but never used.
Replace the below
JTextField t1 = new JTextField("Enter country...");
t1.setBounds(50, 100, 200, 30);
window.add(t1);
With
textfield = new JTextField("Enter country...");
textfield.setBounds(50, 100, 200, 30);
window.add(textfield);

Reload the JFrame or JLabel

Im developing an little "clicker" but, if i press the button, and i should get 1+ Score, it dont work! Is there any way to reload or anything else?
Heres my code: (ClickEvent)
public class event implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("PRESS");
game.timesClicked.add(1);
points.setText(game.seePoints);
}
}
And there is my JFrame:
public class game extends JFrame
{
public static JButton buttonStart;
JButton buttonCredits;
JButton buttonBack;
JButton buttonLeave;
public static JFrame panel = new game();
public static ArrayList<Integer> timesClicked = new ArrayList<Integer>();
public static JLabel label1;
public static JLabel points;
public static String seePoints = "Deine Knöpfe: " + timesClicked.size();
public game()
{
setLayout(null);
label1 = new JLabel("ButtonClicker");
points = new JLabel(seePoints);
points.setFont(new Font("Tahoma", Font.BOLD, 15));
points.setBounds(0, 0, 200, 200);
label1.setFont(new Font("Tahoma", Font.BOLD, 50));
label1.setBounds(315, 50, 500, 200);
event e1 = new event();
JButton b = new JButton("KNOPF");
b.setBackground(new Color(96, 140, 247));
b.setForeground(Color.WHITE);
b.setFocusPainted(false);
b.setFont(new Font("Tahoma", Font.BOLD, 15));
b.setBounds( 402, 380, 180, 50 );
b.addActionListener(e1);
add(b);
add(label1);
add(points);
}
}
(Sorry For My Bad English)

public static String seePoints = "Deine Knöpfe: " + timesClicked.size();
This is only being called once at the start of your program. When you add to timesClicked, it does not recalculate seePoints.
You will need to set this variable to the correct value every time you click.

GUI building and using different classes Java

So I'm starting a new project and I was wondering how can I setup multiple classes for my different JPanels. It looks very messy in one class. Let me show you the example. I would like the JPanel for a menu screen in it's own class.
import java.awt.EventQueue;
public class TakeAwayLogin {
private JFrame frmTakeAwaySystem;
private JTextField textFieldId;
private JPasswordField passwordField;
/**
* Launch the application.
* #return
*/
public void login() {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
TakeAwayLogin window = new TakeAwayLogin();
window.frmTakeAwaySystem.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public TakeAwayLogin() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmTakeAwaySystem = new JFrame();
frmTakeAwaySystem.setTitle("Take Away System Alpha");
frmTakeAwaySystem.setBounds(100, 100, 450, 300);
frmTakeAwaySystem.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmTakeAwaySystem.getContentPane().setLayout(new CardLayout(0, 0));
final JPanel panelLogin = new JPanel();
frmTakeAwaySystem.getContentPane().add(panelLogin, "name_254735117500687");
panelLogin.setLayout(null);
panelLogin.setVisible(true);
final JLabel lblIncorrect = new JLabel("Incorrect login, try again");
lblIncorrect.setHorizontalAlignment(SwingConstants.CENTER);
lblIncorrect.setFont(new Font("Tahoma", Font.PLAIN, 9));
lblIncorrect.setForeground(Color.RED);
lblIncorrect.setBounds(148, 74, 139, 14);
panelLogin.add(lblIncorrect);
lblIncorrect.setVisible(false);
final JPanel panelPassword = new JPanel();
frmTakeAwaySystem.getContentPane().add(panelPassword, "name_254738265432897");
panelPassword.setLayout(null);
passwordField = new JPasswordField();
passwordField.setBounds(112, 157, 205, 41);
panelLogin.add(passwordField);
passwordField.setHorizontalAlignment(JPasswordField.CENTER);
JButton btnNewButton = new JButton("Lock Application");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
panelPassword.setVisible(false);
panelLogin.setVisible(true);
passwordField.setText("");
textFieldId.disable();
}
});
btnNewButton.setBounds(135, 155, 172, 50);
panelPassword.add(btnNewButton);
panelPassword.setVisible(false);
JButton btnLogin = new JButton("Login");
btnLogin.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String login = textFieldId.getText();
char[] pass = passwordField.getPassword();
String p = new String(pass);
String password = "pass";
if (login.equalsIgnoreCase("milan") && p.equals(password)) {
panelPassword.setVisible(true);
panelLogin.setVisible(false);
}else {
lblIncorrect.setVisible(true);
}
}
});
btnLogin.setBounds(160, 209, 97, 41);
panelLogin.add(btnLogin);
textFieldId = new JTextField();
textFieldId.setBounds(112, 88, 205, 43);
panelLogin.add(textFieldId);
textFieldId.setColumns(10);
textFieldId.setHorizontalAlignment(JTextField.CENTER);
JLabel lblId = new JLabel("Enter the business login:");
lblId.setHorizontalAlignment(SwingConstants.CENTER);
lblId.setBounds(112, 63, 205, 14);
panelLogin.add(lblId);
JLabel lblEnterYourPassword = new JLabel("Enter your password");
lblEnterYourPassword.setHorizontalAlignment(SwingConstants.CENTER);
lblEnterYourPassword.setBounds(148, 142, 139, 14);
panelLogin.add(lblEnterYourPassword);
JPanel panelPizza = new JPanel();
frmTakeAwaySystem.getContentPane().add(panelPizza, "name_254741096954780");
}
}
So help would be great.
Thanks very much.

I don't know why creating a second class would be necessary. If you just want the code to look less messy, then add comment separators between Panels or something to that effect. I think that splitting up the Panels into their own classes would be just cause you to have to write more calls to be able to create the same functionality. But if you must, then make a class within your initiate class and work from there.

Simplifying, you want something like:
public class MyMainJFrame extends JFrame{
private JPanel panel1 = new MyFooPanel();
private JPanel panel2 = new MyBarPanel();
public MyMainPanel(){
initialize();
}
void initialize(){
//init the JFrame
this.setTitle("Take Away System Alpha");
this.setBounds(100, 100, 450, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLayout(new CardLayout(0, 0));
//and add the panels
this.add(panel1);
this.add(panel2);
}
}
// a file for each one
public class MyFooPanel extends JPanel{
private JButton button;
//... add components and logic
}
public class MyBarPanel extends JPanel{
private JTextField field;
//... add components and logic
}
If you want to use specific methods for each custom panel, then change the type of variable for the same name of the custom class.

Java swing, can't get a textfield to show like it supposed to

I am trying to make the text field for quiz_7 set up, however, it is not showning up like the remaning six, i tried putting an parameter as 360, no text field. Changed it 340, but i only see half a textfield.
import java.awt.Container;
import javax.swing.*;
public class QuizEntry {
JPanel textPanel,panelForTextFields;
JLabel Entry_for_Quizes, quiz1, quiz2, quiz3, quiz4, quiz5, quiz6;
JTextField quiz_1, quiz_2, quiz_3, quiz_4, quiz_5, quiz_6;
JTextField quiz_7;
private JLabel quiz7;
public JPanel createContentPane() {
// We create a bottom JPanel to place everything on.
JPanel totalGUI1 = new JPanel();
totalGUI1.setLayout(null);
Entry_for_Quizes = new JLabel("Quiz Entry ");
Entry_for_Quizes.setLocation(0, 0);
Entry_for_Quizes.setSize(400, 400);
Entry_for_Quizes.setHorizontalAlignment(4);
totalGUI1.add(Entry_for_Quizes);
// Creation of a Panel to contain the JLabels
textPanel = new JPanel();
textPanel.setLayout(null);
textPanel.setLocation(10, 35);
textPanel.setSize(100, 600);
totalGUI1.add(textPanel);
// Username Label
quiz1 = new JLabel("Quiz 1");
quiz1.setLocation(-20, 0);
quiz1.setSize(70, 40);
quiz1.setHorizontalAlignment(4);
textPanel.add(quiz1);
// Login Label
quiz2 = new JLabel("Quiz 2");
quiz2.setLocation(-20, 60);
quiz2.setSize(70, 40);
quiz2.setHorizontalAlignment(4);
textPanel.add(quiz2);
// Username Label
quiz3 = new JLabel("Quiz 3");
quiz3.setLocation(-20, 120);
quiz3.setSize(70, 40);
quiz3.setHorizontalAlignment(4);
textPanel.add(quiz3);
// Login Label
quiz4 = new JLabel("Quiz 4");
quiz4.setLocation(-20, 180);
quiz4.setSize(70, 40);
quiz4.setHorizontalAlignment(4);
textPanel.add(quiz4);
// Username Label
quiz5 = new JLabel("Quiz 5");
quiz5.setLocation(-20, 240);
quiz5.setSize(70, 40);
quiz5.setHorizontalAlignment(4);
textPanel.add(quiz5);
// L
quiz6 = new JLabel("Quiz 6");
quiz6.setLocation(-20, 300);
quiz6.setSize(70, 40);
quiz6.setHorizontalAlignment(4);
textPanel.add(quiz6);
quiz7 = new JLabel("Quiz 7");
quiz7.setLocation(-20, 350);
quiz7.setSize(70, 40);
quiz7.setHorizontalAlignment(4);
textPanel.add(quiz7);
//////////////////////////////////////////////////////////////
panelForTextFields = new JPanel();
panelForTextFields.setLayout(null);
panelForTextFields.setLocation(110, 40);
panelForTextFields.setSize(100, 350);
totalGUI1.add(panelForTextFields);
// quiz Textfield
quiz_1 = new JTextField(8);
quiz_1.setLocation(0, 0);
quiz_1.setSize(100, 30);
panelForTextFields.add(quiz_1);
quiz_2 = new JTextField(8);
quiz_2.setLocation(0, 60);
quiz_2.setSize(100, 30);
panelForTextFields.add(quiz_2);
quiz_3 = new JTextField(8);
quiz_3.setLocation(0, 120);
quiz_3.setSize(100, 30);
panelForTextFields.add(quiz_3);
quiz_4 = new JTextField(8);
quiz_4.setLocation(0, 180);
quiz_4.setSize(100, 30);
panelForTextFields.add(quiz_4);
quiz_5 = new JTextField(8);
quiz_5.setLocation(0, 240);
quiz_5.setSize(100, 30);
panelForTextFields.add(quiz_5);
quiz_6 = new JTextField(8);
quiz_6.setLocation(0, 300);
quiz_6.setSize(100, 30);
panelForTextFields.add(quiz_6);
quiz_7 = new JTextField(8);
quiz_7.setLocation(0, 340);
quiz_7.setSize(100, 30);
panelForTextFields.add(quiz_7);
return totalGUI1;
}
private static void createAndShowGUI() {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("Quiz Entry");
QuizEntry demo = new QuizEntry();
frame.setContentPane(demo.createContentPane());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(700, 700);
frame.setVisible(true);
}
public static void main(String[] args) {
// Schedule a job for the event-dispatching thread:
// creating and showing this application's GUI.
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

Basically change size: for panelForTextFields. From 350 to 500 for example.
To make code a bit generic I would write something like:
panelForTextFields.setSize(100, 6*80);
where 6 is count of JTextFields.
If we will go further, I would create list of JTextField like:
List<JTextField> list = new ArrayList<JTextField>();
list.add(quiz_1);
list.add(quiz_2);
list.add(quiz_3);
list.add(quiz_4);
list.add(quiz_5);
list.add(quiz_6);
and after would write:
final int GAP = 40;
panelForTextFields.setSize(100, 6*( quiz_1.getHeight() + GAP));
Since you used the same logic to configure JTextfields you can use now list like:
quiz_1 = new JTextField(8);
panelForTextFields.add(quiz_1);
quiz_2 = new JTextField(8);
panelForTextFields.add(quiz_2);
quiz_3 = new JTextField(8);
panelForTextFields.add(quiz_3);
quiz_4 = new JTextField(8);
panelForTextFields.add(quiz_4);
quiz_5 = new JTextField(8);
panelForTextFields.add(quiz_5);
quiz_6 = new JTextField(8);
panelForTextFields.add(quiz_6);
quiz_7 = new JTextField(8);
panelForTextFields.add(quiz_7);
list.add(quiz_1);
list.add(quiz_2);
list.add(quiz_3);
list.add(quiz_4);
list.add(quiz_5);
list.add(quiz_6);
list.add(quiz_7);
for(int k = 0; k<list.size(); k++){
JTextField f = list.get(k);
f.setLocation(0, k*60);
f.setSize(100, 30);
}
final int GAP = 40;
panelForTextFields.setSize(100, 6*( quiz_1.getHeight() + GAP));

why isn't my Jlabels or Jpanels showing?

i've added a title to my Jframe, and now its blocked everything else, what have I done??
public class addressbook
{
public JFrame frame;
public JButton btnadd, btndelete, btnsave, btnprev, btnnext;
public JPanel panel, pTitle;
public JTextField txtname, txtaddress, txthomeno, txtmobno;
public JLabel JlbName , JlbHtn, JlbMtn, JlbAddress, lblTitle;
public addressbook() {
//sets window
frame = new JFrame();
frame.setTitle("Address Book");
frame.setSize(450, 580);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//sets up panel
panel = new JPanel();
panel.setLayout(null);
frame.getContentPane().add(panel);
pTitle = new JPanel();
pTitle.setLayout(new FlowLayout(FlowLayout.CENTER));
lblTitle = new JLabel("Bournemouth University Address Book");
pTitle.add(lblTitle);
frame.add(pTitle);
//Labels
JlbName = new JLabel("Name:");
JlbName.setBounds(10, 50, 100, 20);
panel.add(JlbName);
JlbHtn = new JLabel("Home Number:");
JlbHtn.setBounds(10, 90, 150, 20);
panel.add(JlbHtn);
JlbMtn = new JLabel("Mobile Number:");
JlbMtn.setBounds(10, 130, 200, 20);
panel.add(JlbMtn);
JlbAddress = new JLabel("Address:");
JlbAddress.setBounds(10, 170, 250, 20);
panel.add(JlbAddress);
//Text Fields
txtname = new JTextField("Name");
txtname.setBounds(120, 50, 200, 20);
panel.add(txtname);
txthomeno = new JTextField("Home Number");
txthomeno.setBounds(120, 90, 200, 20);
panel.add(txthomeno);
txtmobno = new JTextField("Mob Number");
txtmobno.setBounds(120, 130, 200, 20);
panel.add(txtmobno);
txtaddress = new JTextField("Address");
txtaddress.setBounds(120, 170, 250, 20);
panel.add(txtaddress);
frame.setVisible(true);
//Buttons && Button Functions
btnadd = new JButton("Add", new ImageIcon("../files/add.png"));
btnadd.setBounds(180, 350, 100, 50);
btnadd.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent event)
{
}});
panel.add(btnadd);
btndelete = new JButton("Delete", new ImageIcon("../files/delete2.png"));
btndelete.setBounds(180, 450, 100, 50);
btndelete.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent event)
{
}});
panel.add(btndelete);
btnsave = new JButton("Save", new ImageIcon("../files/save.png"));
btnsave.setBounds(180, 400, 100, 50);
btnsave.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent event)
{
}});
panel.add(btnsave);
btnprev = new JButton(new ImageIcon("../files/left.png"));
btnprev.setBounds(180, 300, 100, 50);
btnprev.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent event)
{
}});
panel.add(btnprev);
btnnext = new JButton(new ImageIcon("../files/right.png"));
btnnext.setBounds(180, 250, 100, 50);
btnnext.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent event)
{
}});
panel.add(btnnext);
frame.setVisible(true);
panel.setVisible(true);
}

If you are not using a LayoutManager on purpose (and it looks that way) make sure that you set a location and a size for your component.
pTitle.setLocation(100, 100);
pTitle.setSize(100, 100);
But you should rather remove this line
panel.setLayout(null);
and replace it with something like this:
panel.setLayout(new BorderLayout());
Also, don’t forget to add your pTitle to panel.

Add the label to the panel, don't create a new Panel for it
lblTitle = new JLabel("Bournemouth University Address Book");
lblTitle.setBounds(100, 0, 400, 20);
panel.add(lblTitle);

Try adding your JPanel pTitle to frame.getContentPane() or to the JPanel panel
Edit
Instead of
frame.add(pTitle);
do:
frame.getContentPanel().add(pTitle);
If this very quick fix doesn't help, stick with the answer you've already accepted.

You have to set a LayoutManager for your frame:
frame = new JFrame();
frame.getContentPane().setLayout(FooLayout());