No value is return on the JDialog after clicking ok button

Question

My class that extends to JDialog won't return a value after clicking okay. Could anyone show what I'm doing wrong? I want it to return a value which is a double.

Here's my code:

import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.BorderLayout;
import java.awt.event.*;

public class DepositWindow extends JDialog
{
    private JButton jbtOk;
    private JButton jbtCancel;
    private JLabel  jlbAccountNumber;
    private JTextField jtfAmount;

    public DepositWindow() {
        setModal(true);
        // Create panel p1 for the buttons and set GridLayout
        // Set BorderLayout with horizontal gap 5 and vertical gap 10
        setLayout(new BorderLayout(5, 10));
        JPanel p1 = new JPanel();
        p1.setBorder( new TitledBorder("Actions"));
        p1.setLayout(new FlowLayout(FlowLayout.RIGHT, 1, 1));
        jbtOk = new JButton("OK");
        jbtCancel = new JButton("Cancel");
        p1.add(jbtOk);
        p1.add(jbtCancel);

        this.add(p1,BorderLayout.SOUTH);

        JPanel p2 = new JPanel(new GridLayout(2,2));
        p2.setBorder( new TitledBorder("Account"));
        p2.add(new JLabel("Account Number"));
        jlbAccountNumber = new JLabel("*****-56");
        p2.add(jlbAccountNumber);
        p2.add(new JLabel("Amount"));
        jtfAmount = new JTextField(10);
        p2.add(jtfAmount);

        // add contents into the frame
        add(p2, BorderLayout.CENTER);

        jbtOk.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                setVisible(false);
            }
        });
  }

  public double getAmount(){
      return Double.parseDouble(jtfAmount.getText());
    }

  /** Main method */
  public static void main(String[] args) {
    DepositWindow frame = new DepositWindow();
    frame.setTitle("Deposit Window");
    frame.pack();
    frame.setLocationRelativeTo(null); // Center the frame
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
    double amount = frame.getAmount();
  }
 }

It's giving me these errors when I run my main Error:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1011)
    at java.lang.Double.parseDouble(Double.java:540)
    at DepositWindow.getAmount(DepositWindow.java:51)
    at AccountWindow.<init>(AccountWindow.java:48)
    at LoginWindow.login(LoginWindow.java:67)
    at LoginWindow.access$000(LoginWindow.java:16)
    at LoginWindow$1.actionPerformed(LoginWindow.java:55)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:708)
    at java.awt.EventQueue$4.run(EventQueue.java:706)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

Answer 1

Your stack trace says it all - you are getting a NumberFormatException when trying to parse a string into a double - Double.parseDouble(jtfAmount.getText()).

Javadoc says:

Throws:
NullPointerException - if the string is null
NumberFormatException - if the string does not contain a parsable double.

So use a try/catch block to handle such cases.

Also, you could have some sort of validation in your dialog, if you don't want to wait until the dialog is closed to see if the input value is ok.

Answer 2

The actual problem is not with the number format but closing operation, replace your DefaultCloseOperation statement with the following it worked for me. since it is a JDialog it should be disposed :)

frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);