Java GUI 计算器的实现

注：文章原地址：blog.csdn.net/weixin_5237…

Windows系统自带计算器的简单实现

1. 布局方式：

整体采用BorderLayout布局方式，分为NORTH和SOUTH两部分。

NORTH部分为一个文本域（JTextArea）。

SOUTH部分采用GridLayout布局，分成6行4列，用来添加按钮。

2. 代码结构

代码分为GUI界面的实现和事件的处理两部分。 GUI界面重点为按钮的添加（采用循环方式，可减少代码量）。 事件处理重点是准确获取事件发生源和文本域字符串的获取和设置。

3. 代码实现

GUI界面

package com.calculator.exer1;

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

public class Calculator extends JFrame {
    JButton jb;
    Calculator(){
        super("计算器");
        setResizable(false);    //设置窗口尺寸不能改变
//        setSize(365,650);
//        setLocation(1000,50);
        setBounds(1000,50,365,650);
        surface();
        setVisible(true);
    }
    public void surface(){
        setLayout(new BorderLayout());  //设置整体布局为BorderLayout
        //NORTH部分
        JPanel topPanel = new JPanel();
        JTextArea jt = new JTextArea("0",5,22);
        jt.setFont(new Font("宋体",Font.BOLD,30));
        jt.setEditable(false);
        topPanel.add(jt);
        add(topPanel,BorderLayout.NORTH);
        //SOUTH部分
        JPanel bottomPanel = new JPanel();
        bottomPanel.setLayout(new GridLayout(6,4,6,6));
        String[] strs = {
                "%","CE","C","Del",
                "1/x","x²","√x","/",
                "7","8","9","*",
                "4","5","6","-",
                "1", "2","3","+",
                "+/_","0",".","="
        };
        Event event = new Event(jt);    //监听器的创建
        for(int i =0;i < strs.length; i++){
            if(strs[i].equals("=")){
                jb = new JButton(strs[i]);
                jb.setBackground(Color.blue);     //设置背景颜色
                jb.setForeground(Color.white);    //设置字体颜色
                jb.setFont(new Font("宋体",Font.BOLD,30));//设置字体参数
                bottomPanel.add(jb);
                jb.addActionListener(event);
            }else{
                jb = new JButton(strs[i]);
                jb.setBackground(Color.white);
                jb.setFont(new Font("宋体",Font.BOLD,20));
                bottomPanel.add(jb);
                jb.addActionListener(event);
            }
        }
        add(bottomPanel);
    }

    public static void main(String[] args) {
        new Calculator();
    }
}

事件处理

package com.calculator.exer1;

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

public class Event implements ActionListener {
    JTextArea jt = new JTextArea();
    StringBuffer sb = new StringBuffer();
    Event(JTextArea jt){
        this.jt = jt;
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();  //返回与此动作相关的命令字符串。
        String temp = jt.getText();
        switch (command){
            case "1": case "2": case "3": case "4": case "5":
            case "6": case "7": case "8": case "9": case "0":
            case "+": case "-": case "*": case "/": case ".":
                sb.append(command);
                jt.setText(sb.toString());
                break;
            case "%": case "CE": case "C":
                sb.setLength(0);
                jt.setText("0");
                break;
            case "Del":
                sb.deleteCharAt(sb.length()-1);
                jt.setText(temp.substring(0,temp.length()-1));  //返回该字符串的子字符串(去除原字符串尾部的一位，从而达到删除最后一位的目的)
                break;
            case "1/x":
                double ans1 = Double.valueOf(jt.getText());
                jt.setText(String.valueOf(1 / ans1));
                sb.setLength(0);
                break;
            case "x²":
                double ans2 = Double.valueOf(jt.getText());
                jt.setText(String.valueOf(Math.pow(ans2,2)));
                sb.setLength(0);
                break;
            case "√x":
                double ans3 = Double.valueOf(jt.getText());
                jt.setText(String.valueOf(Math.pow(ans3,0.5)));
                sb.setLength(0);
                break;
            case "=":
                if (temp.contains("+")) {
                    String[] string = temp.split("\\+"); //分隔字符串
                    double num1 = Double.valueOf(string[0]);
                    double num2 = Double.valueOf(string[1]);
                    jt.setText(String.valueOf(num1 + num2));
                    sb.setLength(0);
                } else if (temp.contains("-")) {
                    String[] string = temp.split("-");
                    double num1 = Double.valueOf(string[0]);
                    double num2 = Double.valueOf(string[1]);
                    jt.setText(String.valueOf(num1 - num2));
                    sb.setLength(0);
                } else if (temp.contains("*")) {
                    String[] string = temp.split("\\*");
                    double num1 = Double.valueOf(string[0]);
                    double num2 = Double.valueOf(string[1]);
                    jt.setText(String.valueOf(num1 * num2));
                    sb.setLength(0);
                } else if (temp.contains("/")) {
                    String[] string = temp.split("\\/");
                    double num1 = Double.valueOf(string[0]);
                    double num2 = Double.valueOf(string[1]);
                    jt.setText(String.valueOf(num1 / num2));
                    sb.setLength(0);
                }
                break;
        }
    }
}

4. 最终呈现