用JButton按钮退出对话框JDialog

Question

代码如下：import javax.swing.*;
import java.awt.*;
import java.awt.event.*;public class DialogTest
{
protected Mainframe mainframe;

public DialogTest()
{
mainframe=new Mainframe("Test");
}

public class Mainframe extends JFrame
{
protected Subdialog sub;
protected JButton ok=new JButton("OK");
public Mainframe(String title)
{
super(title);
setLayout(new FlowLayout());
setSize(200,200);
add(ok);
ok.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
sub=new Subdialog(mainframe,"dialog",true);
}
}
);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public class Subdialog extends JDialog
{
JButton dis=new JButton("dispose");
public Subdialog(Mainframe main,String title,boolean mode)
{
super(main,title,mode);
setSize(60,60);
add(dis);
setVisible(true);
dis.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
sub.dispose();
}
}
);
}
}
}

public static void main(String[] args)
{
DialogTest app=new DialogTest();
}
}
如果是子窗口是Frame的话没有问题，如果是JDialog的话要怎么办？谢谢！

Answer 1

不是很懂你的问意，用dispose();方法就可以退出并关闭JDialog了。

Answer 2

子窗体中按钮添加监听的代码要在子窗体前面：                dis.addActionListener(new ActionListener()
                {
                    public void actionPerformed(ActionEvent e)
                    {
                        sub.dispose();
                    }
                }
                );
                setVisible(true);
因为你的JDialog是模态窗体，所以调用了setVisible(true)后，
后面的dis.addActionListener并没有执行，所以要放到setVisible前面

Answer 3

这个问题前几天已经有人问过了。JDialog(Mainframe main,String title,boolean mode)创建的是模态Dialog，setVisble之后，当前线程就被阻塞，这就意味这你的Button的Action监听没有执行。就像上面说的，你要把所有的事情做完之后，才能调用setVisible

Answer 4

这个，照着你说的改了，编译通过但是执行是出现Exception，貌似是指针错误，就是在sub.dispose（）；那行.麻烦帮忙看看
E:\MyDoc\JAVA>java DialogTest
Exception occurred during event dispatching:
java.lang.NullPointerException
        at DialogTest$Mainframe$Subdialog$1.actionPerformed(DialogTest.java:49)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Sour
ce)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.Dialog$1.run(Unknown Source)
        at java.awt.Dialog$3.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.awt.Dialog.show(Unknown Source)
        at java.awt.Component.show(Unknown Source)
        at java.awt.Component.setVisible(Unknown Source)
        at java.awt.Window.setVisible(Unknown Source)
        at java.awt.Dialog.setVisible(Unknown Source)
        at DialogTest$Mainframe$Subdialog.<init>(DialogTest.java:53)
        at DialogTest$Mainframe$1.actionPerformed(DialogTest.java:28)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Sour
ce)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)

Answer 5

setVisible(true);之后，线程就被阻塞，赋值操作并没有完成也就是说，在关闭之前 sub = null，再说 直接写 dispose();就可以了，没有必要 sub.dispose();

Answer 6

原来是这样，谢谢！这下问题解决诶了。结贴了。感谢gongfuliang和各位的帮助！