Java GUI编程实例-简易计算器

//计算器类
class Calculator extends Frame{
    public Calculator() {
        //3个文本框
        TextField num1 = new TextField(10);
        TextField num2 = new TextField(20);
        TextField num3 = new TextField(30);
        
        //1个按钮
        Button button = new Button("=");
        button.addAcitonListener(new MyCalculatorListener(num1, num2, num3));
        
        //1个标签
        Label lable = new Label("+");
        
        setLayout(new FlowLayout());
        
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        
        setVisible(true);
    }
}

//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. 将和放到第三个框
        num3.setText(""+(n1+n2));
        //3. 清除前2个框
        num1.setText("");
        num2.setText("");
    }
}

这段代码是可以优化的:

//计算器类
class Calculator extends Frame{
    //属性
    TextField num1, num2, num3;
    
    //方法
    public void loadFrame() {
        //3个文本框
        num1 = new TextField(10);
        num2 = new TextField(20);
        num3 = new TextField(30);
        //1个按钮
        Button button = new Button("=");
        //1个标签
        Label lable = new Label("+");
        
        button.addAcitonListener(new MyCalculatorListener(this));
        
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        
        setVisible(true);
    }
}

//监听器类
class MyCalculatorListener implements ActionListener{
    //获取计算器这个对象
    Calculator calculator = null;
    
    public MyCalculatorListener(Calculator calculator) {
        this.calculator = calculator;
    }
    
    @Override
    public void actionPerformed(ActionEvent e) {
        //1. 获得加数和被加数
       int n1 =  Interger.parseInt(calculator.num1.getText());
       int n2 =  Interger.parseInt(calculator.num2.getText());
        //2. 将和放到第三个框
        calculator.num3.setText(""+(n1+n2));
        //3. 清除前2个框
        calculator.num1.setText("");
        calculator.num2.setText(""):
    }
}

完全改造为面向对象： 内部类-更好的包装

class Calculator extends Frame{
    //属性
    TextField num1, num2, num3;
    
    //方法
    public void loadFrame() {
        //3个文本框
        num1 = new TextField(10);
        num2 = new TextField(20);
        num3 = new TextField(30);
        //1个按钮
        Button button = new Button("=");
        //1个标签
        Label lable = new Label("+");
        
        button.addAcitonListener(new MyCalculatorListener());
        
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        
        setVisible(true);
    }
    
    //监听器类
    //内部类最大好处：直接访问外部类属性方法
    private class MyCalculatorListener implements ActionListener {
         @Override
        public void actionPerformed(ActionEvent e) {
        //1. 获得加数和被加数
       int n1 =  Interger.parseInt(calculator.num1.getText());
       int n2 =  Interger.parseInt(calculator.num2.getText());
        //2. 将和放到第三个框
        num3.setText(""+(n1+n2));
        //3. 清除前2个框
        num1.setText("");
        num2.setText(""):
    }
}

学习资源

www.bilibili.com/video/av776…