简易计算器

简易计算器，组合+内部类回顾复习

oop原则：组合，大于继承！

目前代码

package com.hua.demo;

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

public class TestCalc {
    public static void main(String[] args) {
        new Calculator();
    }
}
class Calculator extends Frame {
    public Calculator(){
        //3个文本框
        TextField num1 = new TextField(10);//字符数
        TextField num2 = new TextField(10);//字符数
        TextField num3 = new TextField(20);//字符数

        //1个按钮
        Button button = new Button("=");
        button.addActionListener(new CalculatorListener(num1,num2,num3));

        //1个标签
        Label label = new Label("+");
        //布局
        setLayout(new FlowLayout());

        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        
        pack();
        setVisible(true);

    }
}
//监听器类
class CalculatorListener implements ActionListener{
    //获取三个变量
    private TextField num1,num2,num3;
    public CalculatorListener(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+法运算后，放到第三个框
        num3.setText(""+(n1+n2));

        //清除前两个框
        num1.setText("");
        num2.setText("");
    }
}

完全改造为面向对象写法

package com.hua.demo;

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

public class TestCalc {
    public static void main(String[] args) {
        new Calculator().loadFrame();
    }
}
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(10);
        num3 = new TextField(20);
        //1个按钮
        Button button = new Button("=");
        button.addActionListener(new CalculatorListener(this));
        //1个标签
        Label label = new Label("+");
        //布局
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        pack();
        setVisible(true);
    }
}
//监听器类
class CalculatorListener implements ActionListener{
    //获取计算器这个对象，在一个类中组合另外一个类
    Calculator calculator = null;
    public CalculatorListener(Calculator calculator){
        this.calculator = calculator;
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        //1.获得加数和被加数
        // 2.将这个值+法运算后，放到第三个框
        // 清除前两个框
        int n1 = Integer.parseInt(calculator.num1.getText());
        int n2 = Integer.parseInt(calculator.num2.getText());
        calculator.num3.setText(""+(n1+n2));

        calculator.num1.setText("");
        calculator.num2.setText("");
    }
}

内部类：

• 更好地包装

package com.hua.demo;

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

public class TestCalc {
    public static void main(String[] args) {
        new Calculator().loadFrame();
    }
}
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(10);
        num3 = new TextField(20);
        //1个按钮
        Button button = new Button("=");
        button.addActionListener(new CalculatorListener());
        //1个标签
        Label label = new Label("+");
        //布局
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        pack();
        setVisible(true);
    }
    //监听器类
    //内部类最大的好处就是，可以畅通无阻地访问外部属性和方法！
    private class CalculatorListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent e) {
            //1.获得加数和被加数
            // 2.将这个值+法运算后，放到第三个框
            // 清除前两个框
            int n1 = Integer.parseInt(num1.getText());
            int n2 = Integer.parseInt(num2.getText());
            num3.setText(""+(n1+n2));

            num1.setText("");
            num2.setText("");
        }
    }
}