Java-GUI-简易计算机的三种写法

简易计算器

oop原则：组合大于继承

基础写法

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

//简易计算器
public class TextCalc {
    public static void main(String[] args) {
        new Calculator();
    }
}

//计算器类
class Calculator extends Frame{
    public Calculator() {
        //3个文本框TextField
        TextField num1 = new TextField(10);
        TextField num2 = new TextField(10);
        TextField num3 = new TextField(20);

        //1个按钮Button
        Button button = new Button("=");
        button.addActionListener(new MyCalculator(num1,num2,num3) );
        //1个标签Label
        Label label = new Label("+");

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

        pack();
        setVisible(true);
    }

}

//计算器监听类
class MyCalculator implements ActionListener {

    private TextField num1,num2,num3;

    public MyCalculator(TextField num1,TextField num2,TextField num3) {
        this.num1=num1;
        this.num2=num2;
        this.num3=num3;
    }

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

        //进行加法运算，结果放到第三个框
        num3.setText(""+(n1+n2));


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

完全面向对象

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

//简易计算器
public class TextCalc {
    public static void main(String[] args) {
        new Calculator().loadFrame();
    }
}

//计算器类
class Calculator extends Frame{

    //属性
    TextField num1,num2,num3;
    //方法
    public void loadFrame(){
        //3个文本框TextField
        num1 = new TextField(10);
        num2 = new TextField(10);
        num3 = new TextField(20);
        Button button = new Button("=");
        Label label = new Label("+");

        button.addActionListener(new MyCalculator(this) );

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

        pack();
        setVisible(true);
    }

}

//计算器监听类
class MyCalculator implements ActionListener {

    Calculator calculator = null;

    public MyCalculator(Calculator calculator) {
        this.calculator=calculator;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        //1获得加数和被加数
        //2进行加法运算，结果放到第三个框
        //3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

• 更好的包装

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

//简易计算器
public class TextCalc {
    public static void main(String[] args) {
        new Calculator().loadFrame();
    }
}

//计算器类
class Calculator extends Frame{

    //属性
    TextField num1,num2,num3;
    //方法
    public void loadFrame(){
        //3个文本框TextField
        num1 = new TextField(10);
        num2 = new TextField(10);
        num3 = new TextField(20);
        Button button = new Button("=");
        Label label = new Label("+");

        button.addActionListener(new MyCalculator() );

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

        pack();
        setVisible(true);
    }

    //内部类最大的好处，就是可以畅通无阻的访问外部类的属性和方法，降低了编码成本
    private  class MyCalculator implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            //1获得加数和被加数
            //2进行加法运算，结果放到第三个框
            //3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("");
        }
    }
}