计算器

OOP原则：组合，大于继承

目前代码

public class TestCalc {
    public static void main(String[] args) {
        new Calculator();
    }
}
//计算器类
class Calculator extends Frame{
    public Calculator(){
        //3个文本框
        TextField num1 = new TextField(10);//字符数
        TextField num2 = new TextField(10);
        TextField num3 = new TextField(20);
        //1个按钮
        Button button = new Button("=");
        button.addActionListener(new MyCalculatorListener(num1,num2,num3));
        //1个标签
        Label label = new Label("+");//加号
        //布局
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        pack();
        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、将这个值加法运算后，放到第三个框
        num3.setText(""+(n1+n2));
        //3、清除前两个框
        num1.setText("");
        num2.setText("");
    }
}

完全改造为面向对象写法

public class TestCalcPlus {
    public static void main(String[] args) {
        new Calculator1().loadFrame();
    }
}
//计算器类
class Calculator1 extends Frame{
    //属性
    TextField num1,num2,num3;
    //方法
    public void loadFrame(){
        //3个文本框
        num1 = new TextField(10);//字符数
        num2 = new TextField(10);
        num3 = new TextField(20);
        //1个按钮
        Button button = new Button("=");
        button.addActionListener(new MyCalculatorListener1(this));
        //1个标签
        Label label = new Label("+");//加号
        //布局
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        pack();
        setVisible(true);
    }
}
//监听器类
class MyCalculatorListener1 implements ActionListener{
    //获取计算器这个对象，在一个类中组合另一个类
    Calculator1 calculator1=null;
    public MyCalculatorListener1(Calculator1 calculator1) {
        this.calculator1=calculator1;
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        //1、获得加数和被加数
        int n1 = Integer.parseInt(calculator1.num1.getText());
        int n2 = Integer.parseInt(calculator1.num2.getText());
        //2、将这个值加法运算后，放到第三个框
        calculator1.num3.setText(""+(n1+n2));
        //3、清除前两个框
        calculator1.num1.setText("");
        calculator1.num2.setText("");
    }
}

内部类

更好的包装

public class TestCalc2 {
    public static void main(String[] args) {
        new Calculator2().loadFrame();
    }
}
//计算器类
class Calculator2 extends Frame {
    //属性
    TextField num1,num2,num3;
    //方法
    public void loadFrame(){
        //3个文本框
        num1 = new TextField(10);//字符数
        num2 = new TextField(10);
        num3 = new TextField(20);
        //1个按钮
        Button button = new Button("=");
        button.addActionListener(new MyCalculatorListener2());
        //1个标签
        Label label = new Label("+");//加号
        //布局
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        pack();
        setVisible(true);
    }
    //监听器类
    //内部类的最大的好处就是可以畅通无阻的访问外部类的属性和方法
    private class MyCalculatorListener2 implements ActionListener {
        @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、将这个值加法运算后，放到第三个框
            num3.setText("" + (n1 + n2));
            //3、清除前两个框
            num1.setText("");
            num2.setText("");
        }
    }
}