Java AWT |窗口状态监听器

WindowStateListener 是Java.awt.event 包的一部分。它是一个处理窗口状态事件的接口。当与之关联的框架或窗口被图标化或最大化时，此接口返回一个事件。
类的抽象函数：

• windowStateChanged(WindowEvent e) : 当窗口状态改变时调用。
  

下面的程序说明了 WindowStateListener：

1. 处理窗口事件的Java程序
   

Java

// Java Program to handle window events
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class listener1 extends JFrame implements WindowStateListener {
    listener1()
    {
        super("main frame");
        setSize(500, 500);
 
        // create a sub frame
        JFrame f = new JFrame("sub");
 
        // add window state listener
        f.addWindowStateListener(this);
 
        // set size of window
        f.setSize(200, 200);
 
        show();
        f.show();
    }
 
    // if state of window is changed
    public void windowStateChanged(WindowEvent e)
    {
        JOptionPane.showMessageDialog(this, "window state changed");
    }
    // main class
    public static void main(String args[])
    {
        listener1 l = new listener1();
    }
}

1. 输出：
   

1. 处理窗口事件并识别它们的Java程序：
   

Java

// Java Program to handle window events and identify them
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class listener extends JFrame implements WindowStateListener {
    // label
    JLabel l;
    JLabel l1;
 
    listener()
    {
        super("main frame");
        setSize(500, 500);
 
        // create a sub frame
        JFrame f = new JFrame("sub");
 
        // add window state listener
        f.addWindowStateListener(this);
 
        // set size of window
        f.setSize(200, 200);
 
        // create a label
        JLabel lo = new JLabel("old state : ");
        JLabel lo1 = new JLabel("new state : ");
 
        l = new JLabel("");
        l1 = new JLabel("");
 
        // create a panel
        JPanel p = new JPanel();
 
        p.add(lo);
        p.add(l);
        p.add(lo1);
        p.add(l1);
        add(p);
 
        show();
        f.show();
    }
 
    // if state of window is changed
    public void windowStateChanged(WindowEvent e)
    {
        int s = e.getOldState(), s1 = e.getNewState();
 
        // for old state
        if (s == Frame.ICONIFIED)
            l.setText("window iconified");
 
        if (s == Frame.MAXIMIZED_BOTH)
            l.setText("window maximized horizontally and vertically");
 
        if (s == Frame.MAXIMIZED_HORIZ)
            l.setText("window maximized horizontally");
 
        if (s == Frame.MAXIMIZED_VERT)
            l.setText("window maximized vertically");
 
        if (s == Frame.NORMAL)
            l.setText("window normal");
 
        // for new state
 
        if (s1 == Frame.ICONIFIED)
            l1.setText("window iconified");
 
        if (s1 == Frame.MAXIMIZED_BOTH)
            l1.setText("window maximized horizontally and vertically");
 
        if (s1 == Frame.MAXIMIZED_HORIZ)
            l1.setText("window maximized horizontally");
 
        if (s1 == Frame.MAXIMIZED_VERT)
            l1.setText("window maximized vertically");
 
        if (s1 == Frame.NORMAL)
            l1.setText("window normal");
    }
 
    // main class
    public static void main(String args[])
    {
        listener l = new listener();
    }
}

1. 输出：
   

注意：以下程序不会在在线编译器中运行，请使用离线 IDE
参考：https: Java/awt/event/WindowStateListener.html