java窗体程序复习一

案例显示了对控件的监听事件的不同使用方法。
方法一：

package Component;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Buju5 extends JFrame implements ActionListener {


    JButton btn1=new JButton("north");
    JButton btn2=new JButton("south");
    JButton btn3=new JButton("east");
    JButton btn4=new JButton("west");
    JLabel j1=new JLabel("进行按钮操作");
    Buju5(){
        setLayout(new BorderLayout());

        add(btn1,BorderLayout.NORTH);
        add(btn2,BorderLayout.SOUTH);
        add(btn3,BorderLayout.EAST);
        add(btn4,BorderLayout.WEST);
        add(j1,BorderLayout.CENTER);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        btn1.addActionListener(this);
        btn2.addActionListener(this);
        btn3.addActionListener(this);
        btn4.addActionListener(this);

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if(e.getSource()==btn1){
            j1.setText("north");
            btn1.setVisible(false);
            btn2.setVisible(true);
            btn3.setVisible(true);
            btn4.setVisible(true);
        }else if(e.getSource()==btn2){
            j1.setText("south");
            btn2.setVisible(false);
            btn1.setVisible(true);
            btn3.setVisible(true);
            btn4.setVisible(true);
        }
        else if(e.getSource()==btn3){
            j1.setText("east");
            btn2.setVisible(true);
            btn1.setVisible(true);
            btn3.setVisible(false);
            btn4.setVisible(true);
        }else if(e.getSource()==btn4){
            j1.setText("west");
            btn2.setVisible(true);
            btn1.setVisible(true);
            btn3.setVisible(true);
            btn4.setVisible(false);
        }
    }

    public static void main(String[] args) {
        Buju5 buju5=new Buju5();
        buju5.setBounds(300,250,300,200);
    }
}

方法二：

package Component;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ya extends JFrame implements ActionListener {

    JButton[] b=new JButton[4];
    JTextField textField=new JTextField(8);
    ya(){
        b[0]=new JButton("north");
        b[1]=new JButton("south");
        b[2]=new JButton("east");
        b[3]=new JButton("west");
        setLayout(new BorderLayout());
        add(b[0], BorderLayout.NORTH);
        add(b[1],BorderLayout.SOUTH);
        add(b[2],BorderLayout.EAST);
        add(b[3],BorderLayout.WEST);

        add(textField,BorderLayout.CENTER);
        for(int i=0;i<4;i++){
            b[i].addActionListener(this);
        }

        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100,100,300,300);
    }


    @Override
    public void actionPerformed(ActionEvent e) {
        for(int i=0;i<4;i++){
            String str=textField.getText();
            if(b[i]==e.getSource()){
                textField.setText("btn "+str+" i\n");
                b[i].setVisible(false);
            }else{
                b[i].setVisible(true);
            }
        }
    }

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

方法三：

package Component;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ma extends JFrame implements ActionListener {

    JButton btn1=new JButton("north");
    JButton btn2=new JButton("south");
    JButton btn3=new JButton("east");
    JButton btn4=new JButton("west");
    JLabel j1=new JLabel("进行按钮操作");
    ma(){
        setLayout(new BorderLayout());

        add(btn1,BorderLayout.NORTH);
        add(btn2,BorderLayout.SOUTH);
        add(btn3,BorderLayout.EAST);
        add(btn4,BorderLayout.WEST);
        add(j1,BorderLayout.CENTER);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        btn1.addActionListener(this);
        btn2.addActionListener(this);
        btn3.addActionListener(this);
        btn4.addActionListener(this);

    }
    @Override
    public void actionPerformed(ActionEvent e) {
        int n=0;
        if(e.getSource()==btn1){
            n=1;
        }else if(e.getSource()==btn2){
            n=2;
        }else if(e.getSource()==btn3){
            n=3;
        }else if(e.getSource()==btn4){
            n=4;
        }

        switch (n){
            case 1:
                j1.setText("north");
                btn1.setVisible(false);
                btn2.setVisible(true);
                btn3.setVisible(true);
                btn4.setVisible(true);
                break;
            case 2:
                j1.setText("south");
                btn2.setVisible(false);
                btn1.setVisible(true);
                btn3.setVisible(true);
                btn4.setVisible(true);
                break;
            case 3:
                j1.setText("east");
                btn2.setVisible(true);
                btn1.setVisible(true);
                btn3.setVisible(false);
                btn4.setVisible(true);
                break;
            case 4:
                j1.setText("west");
                btn2.setVisible(true);
                btn1.setVisible(true);
                btn3.setVisible(true);
                btn4.setVisible(false);
                break;
        }
    }

    public static void main(String[] args) {
        ma ma=new ma();
        ma.setBounds(100,100,300,300);
    }
}