關於Java WindowListener的問答

Question

如果您有WindowListener，則每當窗口關閉時都會發生windowDeactivated(WindowEvent)事件，或者windowClosing(WindowEvent)發生時不會發生windowDeactivated(WindowEvent)。也就是說，窗口關閉是窗口關閉的一部分嗎？

最後，將一個windowClosed(WindowEvent)總是（通常）遵循windowClosing(WindowEvent)？

Answer 1

假設JFrame，結果似乎取決於setDefaultCloseOperation();獲得WINDOW_CLOSED事件需要「在窗口上呼叫處理」，例如，通過DISPOSE_ON_CLOSE，如提到here。

import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.EventQueue; 
import java.awt.event.WindowAdapter; 
import java.awt.event.WindowEvent; 
import java.util.Random; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 

/** @see http://stackoverflow.com/questions/2141325 */ 
public class MyPanel extends JPanel { 

    private static final Random RND = new Random(); 
    private static final WindowAdapter listener = new WindowAdapter() { 

     @Override 
     public void windowClosed(WindowEvent e) { 
      print(e); 
     } 

     @Override 
     public void windowClosing(WindowEvent e) { 
      print(e); 
     } 

     @Override 
     public void windowDeactivated(WindowEvent e) { 
      print(e); 
     } 

     private void print(WindowEvent e) { 
      System.out.println(e.getWindow().getName() + ":" + e); 
     } 
    }; 

    public MyPanel() { 
     this.setBackground(new Color(RND.nextInt())); 
    } 

    @Override 
    public Dimension getPreferredSize() { 
     return new Dimension(320, 240); 
    } 

    private static void create() { 
     for (int i = 0; i < 2; i++) { 
      JFrame f = new JFrame(); 
      f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 
      f.setTitle(String.valueOf(i)); 
      f.add(new MyPanel()); 
      f.addWindowListener(listener); 
      f.pack(); 
      f.setLocationRelativeTo(null); 
      f.setVisible(true); 
     } 
    } 

    public static void main(String[] args) { 
     EventQueue.invokeLater(new Runnable() { 

      @Override 
      public void run() { 
       create(); 
      } 
     }); 
    } 
}