java事件監聽機制

1.簡單的事件監聽

package demo2;

/*
 * java事件監聽機制
 */
import java.awt.*;
import javax.swing.*;
import java.awt.Event;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.nio.ByteOrder;

public class Demo1 extends JFrame implements ActionListener {
    JPanel m;
    JButton jb1, jb2;

    public static void main(String[] args) {
        Demo1 demo = new Demo1();
    }

    public Demo1() {
        m = new JPanel();
        jb1 = new JButton("黑色");
        jb2 = new JButton("紅色");
        this.add(jb1, BorderLayout.NORTH);
        m.setBackground(Color.BLACK);
        this.add(m);
        this.add(jb2, BorderLayout.SOUTH);
        // 註冊監聽
        jb1.addActionListener(this);
        jb2.addActionListener(this);
        // 指定action命令
        jb1.setActionCommand("aa");
        jb2.setActionCommand("bb");

        this.setSize(400, 300);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // 判斷哪一個按鈕被點擊
        if (e.getActionCommand().equals("aa")) {
            System.out.println("點擊黑色");
            m.setBackground(Color.BLACK);
        } else if (e.getActionCommand().equals("bb")) {
            System.out.println("點擊紅色");
            m.setBackground(Color.red);
        } else {
            System.out.println("點擊錯誤");
        }
    }
}

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2.設置普通類Cat進行監聽

package demo2;

/*
 * java事件監聽機制
 */
import java.awt.*;
import javax.swing.*;
import java.awt.Event;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.nio.ByteOrder;

public class Demo1 extends JFrame implements ActionListener {
    JPanel m;
    JButton jb1, jb2;
    Cat cat;

    public static void main(String[] args) {
        Demo1 demo = new Demo1();
    }

    public Demo1() {
        cat = new Cat();
        m = new JPanel();
        jb1 = new JButton("黑色");
        jb2 = new JButton("紅色");
        this.add(jb1, BorderLayout.NORTH);
        m.setBackground(Color.BLACK);
        this.add(m);
        this.add(jb2, BorderLayout.SOUTH);
        // 註冊監聽
        jb1.addActionListener(cat);
        jb2.addActionListener(cat);
        // 指定action命令
        jb1.setActionCommand("aa");
        jb2.setActionCommand("bb");

        this.setSize(400, 300);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // 判斷哪一個按鈕被點擊
        if (e.getActionCommand().equals("aa")) {
            System.out.println("點擊黑色");
            m.setBackground(Color.BLACK);
        } else if (e.getActionCommand().equals("bb")) {
            System.out.println("點擊紅色");
            m.setBackground(Color.red);
        } else {
            System.out.println("點擊錯誤");
        }
    }

    // 設計cat內部類
    class Cat implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            if (e.getActionCommand().equals("aa")) {
                System.out.println("點擊黑色");
                m.setBackground(Color.BLACK);
            } else if (e.getActionCommand().equals("bb")) {
                System.out.println("點擊紅色");
                m.setBackground(Color.red);
            } else {
                System.out.println("點擊錯誤");
            }
        }

    }
}

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3.上下左右移動

package demo3;

//橫着x 豎着y
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Demo3 extends JFrame {
    Myframe mp;

    public static void main(String[] args) {
        Demo3 demo = new Demo3();
    }

    public Demo3() {
        mp = new Myframe();
        this.add(mp);
        this.addKeyListener(mp);
        this.setSize(400, 300);

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }
}

// Myframe定義的面板用於繪圖
class Myframe extends JPanel implements KeyListener {
    int x = 10, y = 10;

    public void paint(Graphics g) {
        super.paint(g);
        g.fillOval(x, y, 10, 10);
    }

    @Override
    public void keyPressed(KeyEvent e) {
        // TODO Auto-generated method stub
        if (e.getKeyCode() == KeyEvent.VK_DOWN) {
            y += 2;
            System.out.println("向下移動");
            this.repaint();
        } else if (e.getKeyCode() == KeyEvent.VK_UP) {
            y -= 2;
            System.out.println("向上移動");
            this.repaint();
        } else if (e.getKeyCode() == KeyEvent.VK_LEFT) {
            x -= 2;
            System.out.println("向左移動");
            this.repaint();
        } else if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
            x += 2;
            System.out.println("向右移動");
            this.repaint();
        }
    }

    @Override
    public void keyReleased(KeyEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void keyTyped(KeyEvent arg0) {
        // TODO Auto-generated method stub

    }

}

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