1.事件监听

当某个事件发生的时候，他要干什么

public class TestActionEvent {
    public static void main(String[] args) {
        //按下按钮，触发一些事件
        Frame frame = new Frame();
        Button button = new Button();
        //因为addActionListener需要一个ActionListener，所以我们需要构造一个ActionListener

        MyActionListener myActionListener = new MyActionListener();
        button.addActionListener(myActionListener);
        

        frame.add(button,BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
        windowClose(frame);

    }
    //关闭窗体
    private static void windowClose(Frame frame)
    {
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
}
//事件监听
class MyActionListener implements ActionListener
{

    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("aaa");

    }
}

1.2两个按钮实现同一个监听

ublic class TestActionEvent2 {
    public static void main(String[] args) {
        //两个按钮实现同一个监听
        //  开始  停止
        Frame frame = new Frame("开始--停止");
        Button button1= new Button("start");
        Button button2= new Button("stop");

        //可以显示的定义触发会返回的命令，如果不显示定义，则会走默认的值
        //可以多个按钮只写一个监听类
        button2.setActionCommand("button2-stop");
        MyMintor myMintor = new MyMintor();

        button1.addActionListener(myMintor);
        button2.addActionListener(myMintor);

        frame.add(button1,BorderLayout.NORTH);
        frame.add(button2,BorderLayout.SOUTH);

        frame.pack();
        frame.setVisible(true);

    }
}
class MyMintor implements ActionListener
{

    @Override
    public void actionPerformed(ActionEvent e) {
       // e.getActionCommand();---获得按钮的信息
        System.out.println("按钮被点击了：msg=>"+e.getActionCommand());

    }
}

 2.输入框事件监听

TextField textField = new TextField();

1.设置替换编码

textField.setEchoChar('#');

2.每次输入后清空文本框

field.setText("");

 3.简易计算器

public class TestCalc {
    public static void main(String[] args) {
        new Calculator();
    }
}
//计算器类
class Calculator extends Frame
{
    public Calculator()
    {
        //三个文本框
        TextField num1 = new TextField(10);//字符数
        TextField num2 = new TextField(10);
        TextField num3 = new TextField(20);
        //一个按钮
        Button button = new Button("=");
        button.addActionListener(new MyCalculatorListener(num1,num2,num3));
        //一个标签
        Label label = new Label("+");

        //流式布局
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);

        setVisible(true);
        pack();
    }
}
//监听器类
class MyCalculatorListener implements ActionListener
{
    //获取三个变量
    private TextField num1,num2,num3;
    public MyCalculatorListener(TextField num1,TextField num2,TextField num3){
        this.num1 = num1;
        this.num2 = num2;
        this.num3 = num3;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
    //1.获得加数和被加数
        int n1 = Integer.parseInt(num1.getText());
        int n2 = Integer.parseInt(num2.getText());

        //2.将这两个数运算后，放到第三个框
        num3.setText(""+(n1+n2));
        //3.清除前两个框的数
        num1.setText("");
        num2.setText("");
    }
}