自定义JComboBox：“无限循环事件”当LAF是系统LAF时

本文介绍了自定义JComboBox：“无限循环事件”当LAF是系统LAF时的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我自定义我的JComboBox如下。
程序在默认LAF下运行正常，但每当我将LAF更改为System LAF（另一个LAF，Nimbus，没问题）时，单击按钮后会出现无限循环。我看到actionPerformed方法被无限调用。

请帮我解决这个问题。我使用jdk 1.6.0_33

如果有任何不明确的意思，我很抱歉。我的英语不好

提前致谢。

I customize my JComboBox as follow.The program ran ok with default LAF, but whenever i changed the LAF to System LAF (another LAF, Nimbus, is ok), there was an infinite loop after the button was clicked. I saw that the actionPerformed method was called infinitely.
Please help me solving this problem. I use jdk 1.6.0_33
I'm so sorry if there is any unclear mean. My English is not good
Thanks in advance.

package sig.dw.ui;

import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ComboBoxEditor;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
//import javax.swing.event.EventListenerList;

/**
*
* @author congnh
*/
public class ButtonableComboBox extends JComboBox{

    private ButtonableComboBoxEditor comboBoxEditor;
    public ButtonableComboBox(){
        super();
        comboBoxEditor = new ButtonableComboBoxEditor();
        // eventListenerList = new EventListenerList();
        setEditable(true);
        setEditor(comboBoxEditor);
    }


    public ButtonableComboBox(Object[] items){
        this();
        setModel(new DefaultComboBoxModel(items));
    }


    public void addButtonListener(ActionListener listener){
        comboBoxEditor.addActionListener(listener);
    }


    public void removeButtonListener(ActionListener listener){
        comboBoxEditor.removeActionListener(listener);
    }


    class ButtonableComboBoxEditor implements ComboBoxEditor{
        private JButton button;
        public ButtonableComboBoxEditor(){
            button = new JButton();
        }
        @Override
        public Component getEditorComponent() {
            return button;
        }
        @Override
        public void setItem(Object anObject) {
            if(anObject!=null){
                button.setText(anObject.toString());
            }
        }
        @Override
        public Object getItem() {
            return button.getText();
        }

        @Override
        public void selectAll() {
            throw new UnsupportedOperationException("Not supported yet.");
        }

        @Override
        public void addActionListener(ActionListener l) {
            System.out.println("add new listener");
            button.addActionListener(l);
        }

        @Override
        public void removeActionListener(ActionListener l) {
            button.removeActionListener(l);
        }
    }

    public static void main(String args[]){
        javax.swing.SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run(){
                String[] comboBoxItems = {"Browse","Explorer","Firefox","IE","Chrome","Opera"};
                JFrame frame = new JFrame();
                JPanel panel = new JPanel();
                panel.setLayout(new FlowLayout());
                ButtonableComboBox bcb = new ButtonableComboBox(comboBoxItems);
                bcb.addButtonListener(new ActionListener() {

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        System.out.println(e.getActionCommand());
                    }
                });
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                panel.add(bcb);
                frame.add(panel);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}

推荐答案

参考，我在Mac OS X / Java 1.6.0_37上看到 StackOverflowError for MotifLookAndFeel ，但不是 MetalLookAndFeel ， NimbusLookAndFeel ，或 AquaLookAndFeel 。使用下面的示例和L& F选择器，我得到了下面的堆栈跟踪，因为UI委托以递归方式调用 doClick（）。我没有看到明显的解决方法。

For reference, I see StackOverflowError for MotifLookAndFeel on Mac OS X / Java 1.6.0_37, but not MetalLookAndFeel, NimbusLookAndFeel, or AquaLookAndFeel. Using the example below and the L&F selector seen here, I get the follwing stack trace as the UI delegate recursively invokes doClick(). I don't see an obvious workaround.

附录：我看到的类似 StackOverflowError > Ubuntu 12 / Java 1.6.0_24上的MotifLookAndFeel ，但不是 MetalLookAndFeel ， NimbusLookAndFeel ，或 GTKLookAndFeel 。

Addendum: I see a similar StackOverflowError for MotifLookAndFeel on Ubuntu 12 / Java 1.6.0_24, but not MetalLookAndFeel, NimbusLookAndFeel, or GTKLookAndFeel.


Exception in thread "AWT-EventQueue-0" java.lang.StackOverflowError
  at sun.font.FontManager.getFont2D(Native Method)
  at sun.java2d.SunGraphics2D.checkFontInfo(SunGraphics2D.java:780)
  at sun.java2d.SunGraphics2D.getFontInfo(SunGraphics2D.java:941)
  at sun.java2d.pipe.GlyphListPipe.drawString(GlyphListPipe.java:32)
  at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:3054)
  at sun.swing.SwingUtilities2.drawString(SwingUtilities2.java:517)
  at sun.swing.SwingUtilities2.drawStringUnderlineCharAt(SwingUtilities2.java:538)
  at javax.swing.plaf.basic.BasicButtonUI.paintText(BasicButtonUI.java:294)
  at javax.swing.plaf.basic.BasicButtonUI.paintText(BasicButtonUI.java:319)
  at javax.swing.plaf.basic.BasicButtonUI.paint(BasicButtonUI.java:207)
  at com.sun.java.swing.plaf.motif.MotifButtonUI.paint(MotifButtonUI.java:91)
  at javax.swing.plaf.ComponentUI.update(ComponentUI.java:153)
  at javax.swing.JComponent.paintComponent(JComponent.java:760)
  at javax.swing.JComponent.paint(JComponent.java:1037)
  at javax.swing.JComponent.paintChildren(JComponent.java:870)
  at javax.swing.JComponent.paint(JComponent.java:1046)
  at javax.swing.JComponent.paintChildren(JComponent.java:870)
  at javax.swing.JComponent.paint(JComponent.java:1046)
  at javax.swing.JComponent._paintImmediately(JComponent.java:5106)
  at javax.swing.JComponent.paintImmediately(JComponent.java:4890)
  at javax.swing.JComponent.paintImmediately(JComponent.java:4902)
  at javax.swing.AbstractButton.doClick(AbstractButton.java:352)
  at javax.swing.plaf.basic.BasicRootPaneUI$Actions.actionPerformed(BasicRootPaneUI.java:191)
  at javax.swing.plaf.basic.BasicComboBoxUI$Actions.actionPerformed(BasicComboBoxUI.java:1575)
  at javax.swing.plaf.basic.BasicComboBoxUI$Handler.actionPerformed(BasicComboBoxUI.java:1904)
  at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
  at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
  at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
  at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
  at javax.swing.AbstractButton.doClick(AbstractButton.java:389)
  ...
  at javax.swing.plaf.basic.BasicRootPaneUI$Actions.actionPerformed(BasicRootPaneUI.java:191)
  at javax.swing.plaf.basic.BasicComboBoxUI$Actions.actionPerformed(BasicComboBoxUI.java:1575)
  at javax.swing.plaf.basic.BasicComboBoxUI$Handler.actionPerformed(BasicComboBoxUI.java:1904)
  at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
  at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
  at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
  at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
  at javax.swing.AbstractButton.doClick(AbstractButton.java:389)
  at javax.swing.plaf.basic.BasicRootPaneUI$Actions.actionPerformed(BasicRootPaneUI.java:191)
  at javax.swing.plaf.basic.BasicComboBoxUI$Actions.actionPerformed(BasicComboBoxUI.java:1575)

SSCCE：

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.ComboBoxEditor;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToolBar;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class ButtonableComboBox extends JComboBox {

    private ButtonableComboBoxEditor comboBoxEditor;

    public ButtonableComboBox() {
        comboBoxEditor = new ButtonableComboBoxEditor();
        setEditor(comboBoxEditor);
        setEditable(true);
    }

    public ButtonableComboBox(Object[] items) {
        this();
        setModel(new DefaultComboBoxModel(items));
    }

    public void addButtonListener(ActionListener listener) {
        comboBoxEditor.addActionListener(listener);
    }

    public void removeButtonListener(ActionListener listener) {
        comboBoxEditor.removeActionListener(listener);
    }

    class ButtonableComboBoxEditor implements ComboBoxEditor {

        private JButton button = new JButton();

        @Override
        public Component getEditorComponent() {
            return button;
        }

        @Override
        public void setItem(Object anObject) {
            if (anObject != null) {
                button.setText(anObject.toString());
            }
        }

        @Override
        public Object getItem() {
            return button.getText();
        }

        @Override
        public void selectAll() {
            System.out.println("select all");
            button.requestFocus();
        }

        @Override
        public void addActionListener(ActionListener l) {
            System.out.println("add listener");
            button.addActionListener(l);
        }

        @Override
        public void removeActionListener(ActionListener l) {
            System.out.println("remove listener");
            button.removeActionListener(l);
        }
    }

    public static void main(String args[]) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                String[] comboBoxItems = {
                    "Browse", "Explorer", "Firefox", "IE", "Chrome", "Opera"};
                JFrame frame = new JFrame();
                JPanel panel = new JPanel();
                ButtonableComboBox bcb = new ButtonableComboBox(comboBoxItems);
                bcb.addButtonListener(new ActionListener() {

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        System.out.println(e.getActionCommand());
                    }
                });
                panel.add(bcb);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                // https://stackoverflow.com/a/11949899/230513
                frame.add(createToolBar(frame), BorderLayout.NORTH);
                frame.add(panel);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}

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LaF