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How to use Grouplayout in Java

Hello,
On the website from Oracle, there is an example how to use the GroupLayout manager: http://download.oracle.com/javase/tutorial/uiswing/examples/layout/FindProject/src/layout/Find.java
When I run this one in Netbeans it runs fine, but when I want to use it within my program I get a NullPointerException. What I do is, from a menu from another frame I start a new frame with:

Settings settingsFrame = new Settings("Settings");

The Settings class is attached.
What do I forget or what do I do wrong?
Thanks
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */


import java.awt.event.*;
import java.awt.Component;
import javax.swing.*;
import javax.swing.GroupLayout.*;

public class Settings extends JFrame {
  
  private Alignment LEADING;
  private Alignment BASELINE;

  public Settings(String titel) {
    super(titel);
    setVisible(true);
    addWindowListener(new VensterHandler());

      JLabel label = new JLabel("Find What:");
      JTextField textField = new JTextField();
      JCheckBox caseCheckBox = new JCheckBox("Match Case");
      JCheckBox wrapCheckBox = new JCheckBox("Wrap Around");
      JCheckBox wholeCheckBox = new JCheckBox("Whole Words");
      JCheckBox backCheckBox = new JCheckBox("Search Backwards");
      JButton findButton = new JButton("Find");
      JButton cancelButton = new JButton("Cancel");

      // remove redundant default border of check boxes - they would hinder
      // correct spacing and aligning (maybe not needed on some look and feels)
      caseCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
      wrapCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
      wholeCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
      backCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));

        try {
                    UIManager.setLookAndFeel(
                                  "javax.swing.plaf.metal.MetalLookAndFeel");
                                //  "com.sun.java.swing.plaf.motif.MotifLookAndFeel");
                                //UIManager.getCrossPlatformLookAndFeelClassName());
                } catch (Exception ex) {
                    ex.printStackTrace();
                }


        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setAutoCreateGaps(true);
        layout.setAutoCreateContainerGaps(true);

        layout.setHorizontalGroup(layout.createSequentialGroup()
            .addComponent(label)
            .addGroup(layout.createParallelGroup(LEADING)
                .addComponent(textField)
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(LEADING)
                        .addComponent(caseCheckBox)
                        .addComponent(wholeCheckBox))
                    .addGroup(layout.createParallelGroup(LEADING)
                        .addComponent(wrapCheckBox)
                        .addComponent(backCheckBox))))
            .addGroup(layout.createParallelGroup(LEADING)
                .addComponent(findButton)
                .addComponent(cancelButton))
        );

        layout.linkSize(SwingConstants.HORIZONTAL, findButton, cancelButton);

        layout.setVerticalGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(BASELINE)
                .addComponent(label)
                .addComponent(textField)
                .addComponent(findButton))
            .addGroup(layout.createParallelGroup(LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(BASELINE)
                        .addComponent(caseCheckBox)
                        .addComponent(wrapCheckBox))
                    .addGroup(layout.createParallelGroup(BASELINE)
                        .addComponent(wholeCheckBox)
                        .addComponent(backCheckBox)))
                .addComponent(cancelButton))
        );

        setTitle("Find");

    pack();
   
    
  }

  private class VensterHandler extends WindowAdapter {

    public void windowClosing(WindowEvent e) {
      dispose();
    }
  }
}

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This one very similar form

http://download.oracle.com/javase/tutorial/uiswing/examples/layout/FindProject/src/layout/Find.java

works for me outside of Netbeans.

What did you change?

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

//package layout;

import java.awt.Component;
import javax.swing.*;
import static javax.swing.GroupLayout.Alignment.*;

public class Find extends JFrame {
    public Find() {
        JLabel label = new JLabel("Find What:");;
        JTextField textField = new JTextField();
        JCheckBox caseCheckBox = new JCheckBox("Match Case");
        JCheckBox wrapCheckBox = new JCheckBox("Wrap Around");
        JCheckBox wholeCheckBox = new JCheckBox("Whole Words");
        JCheckBox backCheckBox = new JCheckBox("Search Backwards");
        JButton findButton = new JButton("Find");
        JButton cancelButton = new JButton("Cancel");

        // remove redundant default border of check boxes - they would hinder
        // correct spacing and aligning (maybe not needed on some look and feels)
        caseCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
        wrapCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
        wholeCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
        backCheckBox.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));

        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setAutoCreateGaps(true);
        layout.setAutoCreateContainerGaps(true);

        layout.setHorizontalGroup(layout.createSequentialGroup()
            .addComponent(label)
            .addGroup(layout.createParallelGroup(LEADING)
                .addComponent(textField)
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(LEADING)
                        .addComponent(caseCheckBox)
                        .addComponent(wholeCheckBox))
                    .addGroup(layout.createParallelGroup(LEADING)
                        .addComponent(wrapCheckBox)
                        .addComponent(backCheckBox))))
            .addGroup(layout.createParallelGroup(LEADING)
                .addComponent(findButton)
                .addComponent(cancelButton))
        );

        layout.linkSize(SwingConstants.HORIZONTAL, findButton, cancelButton);

        layout.setVerticalGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(BASELINE)
                .addComponent(label)
                .addComponent(textField)
                .addComponent(findButton))
            .addGroup(layout.createParallelGroup(LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(BASELINE)
                        .addComponent(caseCheckBox)
                        .addComponent(wrapCheckBox))
                    .addGroup(layout.createParallelGroup(BASELINE)
                        .addComponent(wholeCheckBox)
                        .addComponent(backCheckBox)))
                .addComponent(cancelButton))
        );

        setTitle("Find");
        pack();
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    UIManager.setLookAndFeel(
                                  "javax.swing.plaf.metal.MetalLookAndFeel");
                                //  "com.sun.java.swing.plaf.motif.MotifLookAndFeel");
                                //UIManager.getCrossPlatformLookAndFeelClassName());
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
                new Find().setVisible(true);
            }
        });
    }
}

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This is waht I see with that code.
find.PNG
Avatar of P-R-W

ASKER

Only changed some of the order of the statements. For example, I placed "setVisible(true);" on top. This way, i saw it does create a frame. My guess the problem lies in the fact that I start it from another frame
No, I just placed the main method from find into your code - without any other fram - it still gives error
Avatar of P-R-W

ASKER

To be a bit more precise: i copied everything into a class I have reused for several other frames. I then took out the bits that I think i don't need. For example the  public static void main(String args[]). When I got the error, i started to shuffle a bit to see if it would go further, but no luck. The error I get is:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.GroupLayout$ParallelGroup.setChildSize(GroupLayout.java:2523)
        at javax.swing.GroupLayout$ParallelGroup.setValidSize(GroupLayout.java:2511)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout$SequentialGroup.setValidSize(GroupLayout.java:1977)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout$SequentialGroup.setValidSize(GroupLayout.java:1977)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout.calculateAutopadding(GroupLayout.java:1058)
        at javax.swing.GroupLayout.prepare(GroupLayout.java:1037)
        at javax.swing.GroupLayout.preferredLayoutSize(GroupLayout.java:857)
        at java.awt.Container.preferredSize(Container.java:1616)
        at java.awt.Container.getPreferredSize(Container.java:1601)
        at javax.swing.JComponent.getPreferredSize(JComponent.java:1629)
        at javax.swing.JRootPane$RootLayout.preferredLayoutSize(JRootPane.java:903)
        at java.awt.Container.preferredSize(Container.java:1616)
        at java.awt.Container.getPreferredSize(Container.java:1601)
        at javax.swing.JComponent.getPreferredSize(JComponent.java:1629)
        at java.awt.BorderLayout.preferredLayoutSize(BorderLayout.java:702)
        at java.awt.Container.preferredSize(Container.java:1616)
        at java.awt.Container.getPreferredSize(Container.java:1601)
        at java.awt.Window.pack(Window.java:665)
        at General.Settings.<init>(Settings.java:95)
        at tech2.Menu$settingsHandler.actionPerformed(Menu.java:161)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.AbstractButton.doClick(AbstractButton.java:357)
        at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1170)
        at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1211)
        at java.awt.Component.processMouseEvent(Component.java:6038)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
        at java.awt.Component.processEvent(Component.java:5803)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
        at java.awt.Container.dispatchEventImpl(Container.java:2102)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.GroupLayout$ParallelGroup.setChildSize(GroupLayout.java:2523)
        at javax.swing.GroupLayout$ParallelGroup.setValidSize(GroupLayout.java:2511)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout$SequentialGroup.setValidSize(GroupLayout.java:1977)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout$SequentialGroup.setValidSizeNotPreferred(GroupLayout.java:2059)
        at javax.swing.GroupLayout$SequentialGroup.setValidSize(GroupLayout.java:1987)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout.calculateAutopadding(GroupLayout.java:1058)
        at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:897)
        at java.awt.Container.layout(Container.java:1432)
        at java.awt.Container.doLayout(Container.java:1421)
        at java.awt.Container.validateTree(Container.java:1519)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validate(Container.java:1491)
        at java.awt.Window.dispatchEventImpl(Window.java:2427)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.GroupLayout$ParallelGroup.setChildSize(GroupLayout.java:2523)
        at javax.swing.GroupLayout$ParallelGroup.setValidSize(GroupLayout.java:2511)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout$SequentialGroup.setValidSize(GroupLayout.java:1977)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout$SequentialGroup.setValidSizeNotPreferred(GroupLayout.java:2059)
        at javax.swing.GroupLayout$SequentialGroup.setValidSize(GroupLayout.java:1987)
        at javax.swing.GroupLayout$Group.setSize(GroupLayout.java:1553)
        at javax.swing.GroupLayout.calculateAutopadding(GroupLayout.java:1058)
        at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:897)
        at java.awt.Container.layout(Container.java:1432)
        at java.awt.Container.doLayout(Container.java:1421)
        at java.awt.Container.validateTree(Container.java:1519)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validate(Container.java:1491)
        at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:639)
        at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:127)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
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ASKER

Thanks a lot! This worked. Can you also tell me why? I followed the import suggestions from Netbeans.