Java图形界面简单计算器

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#热议# 为什么有人显老，有人显年轻？
刑初素5
2017-11-21 · TA获得超过311个赞
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示例代码如下，请参考：

package test.com.test;

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

public class Cal {

    TextField tf = new TextField(40);       //显示文本框
    StringBuffer s1 = new StringBuffer();   //记录运算数字，以及保留结果
    StringBuffer s2 = new StringBuffer();   //记录运算数字，保留上一个输入的数字或运算结果
    static String flag = new String();      //标记运算符号：+，-，*，/
    boolean start = true;   //标记运算开始或结束,保证一次运算之后，第二次进行运算时能同时清空显示界面，即s1为空

    public void init(){
        //主界面
        JFrame f = new JFrame("计算器");
        JPanel p1 = new JPanel();
        p1.add(tf);
        f.add(p1,BorderLayout.NORTH);
        JPanel p2 = new JPanel();
        p2.setLayout(new GridLayout(1,3));
        //动作监听器
        ActionListener listen =new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {

                //输入数字0~9
                if(arg0.getActionCommand()=="0"){

                    if(!s1.toString().equals(new String())){
                        if(!start){
                            //s1清零，保证可以重新输入数字
                            s1.delete(0, s1.length());
                        }
                        start = true;
                        tf.setText(s1.append("0").toString());
                    }   
                }
                if(arg0.getActionCommand()=="1"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("1").toString());
                }
                if(arg0.getActionCommand()=="2"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("2").toString());
                }
                if(arg0.getActionCommand()=="3"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("3").toString());
                }
                if(arg0.getActionCommand()=="4"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("4").toString());
                }
                if(arg0.getActionCommand()=="5"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("5").toString());
                }
                if(arg0.getActionCommand()=="6"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("6").toString());
                }
                if(arg0.getActionCommand()=="7"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("7").toString());
                }
                if(arg0.getActionCommand()=="8"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("8").toString());
                }
                if(arg0.getActionCommand()=="9"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    tf.setText(s1.append("9").toString());
                }
                //输入小数点
                if(arg0.getActionCommand()=="."){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start=true;
                    if(s1.toString().equals(new String()))
                        tf.setText(s1.append("0.").toString());
                    else if(s1.length()==1&&s1.charAt(0)=='-')
                        tf.setText(s1.append("0.").toString());
                    else
                        tf.setText(s1.append(".").toString());
                }
                //输入负号
                if(arg0.getActionCommand()=="+/-"){
                    if(!start){
                        s1.delete(0, s1.length());
                    }
                    start = true;
                    if(s1.toString().equals(new String()))
                        tf.setText(s1.append('-').toString());
                }
                //退格Backspace
                if(arg0.getActionCommand()=="Backspace"){
                    start = true;
                    if(s1.length()!=0){
                        //删除最后输入的一位
                        s1.deleteCharAt(s1.length()-1);
                        tf.setText(s1.toString());
                    }
                }
                //归零CE
                if(arg0.getActionCommand()=="CE"){
                    //清空所有，start标记设为true
                    start = true;
                    s1.delete(0, s1.length());
                    s2.delete(0, s2.length());
                    tf.setText(s1.toString());
                }
                //清除C
                if(arg0.getActionCommand()=="C"){
                    //清空当前输入，即s1清零
                    start = true;
                    s1.delete(0, s1.length());
                    tf.setText(s1.toString());
                }
                //加号
                if(arg0.getActionCommand()=="+"){
                    start = true;
                    flag="+";
                    //s2接收s1的值
                    s2.append(String.valueOf(s1.toString()));
                    //s1清零，重新接收下一个数据
                    s1.delete(0, s1.length());
                    tf.setText(s1.toString());
                }
                //减号
                if(arg0.getActionCommand()=="-"){
                    start = true;
                    flag="-";
                    s2.append(String.valueOf(s1.toString()));
                    s1.delete(0, s1.length());
                    tf.setText(s1.toString());
                }
                //乘号
                if(arg0.getActionCommand()=="*"){
                    start = true;
                    flag="*";
                    s2.append(String.valueOf(s1.toString()));
                    s1.delete(0, s1.length());
                    tf.setText(s1.toString());
                }
                //除号
                if(arg0.getActionCommand()=="/"){
                    start = true;
                    flag="/";
                    s2.append(String.valueOf(s1.toString()));
                    s1.delete(0, s1.length());
                    tf.setText(s1.toString());
                }
                //开根号
                if(arg0.getActionCommand()=="sqrt"){
                    start =false;
                    double s=Double.parseDouble(s1.toString());
                    s1.delete(0, s1.length());
                tf.setText(s1.append(String.valueOf(Math.sqrt(s))).toString());
                }
                //求%
                if(arg0.getActionCommand()=="%"){
                    start =false;
                    double s=Double.parseDouble(s1.toString());
                    s1.delete(0, s1.length());
                    tf.setText(s1.append(String.valueOf(s/100)).toString());
                }
                //求1/x
                if(arg0.getActionCommand()=="1/x"&&!s1.toString().equals(new String())&&Double.parseDouble(s1.toString())!=0){
                    start =false;
                    double s=Double.parseDouble(s1.toString());
                    s1.delete(0, s1.length());
                    tf.setText(s1.append(String.valueOf(1/s)).toString());
                }
                //求结果
                if(arg0.getActionCommand()=="="&&s1.length()!=0&&s2.length()!=0){
                    //start标记为false
                    start =false;
                    //分别获取s1和s2的值
                    double s4=Double.parseDouble(s1.toString()); 
                    double s3=Double.parseDouble(s2.toString());
                    //清空s1和s2，便于开始下一次运算
                    s1.delete(0, s1.length());
                    s2.delete(0, s2.length());
                    //四则运算
                    if(flag=="+"){
                        tf.setText(s1.append(String.valueOf(s3+s4)).toString());
                    }
                    if(flag=="-"){
                        tf.setText(s1.append(String.valueOf(s3-s4)).toString());
                    }
                    if(flag=="*"){
                        tf.setText(s1.append(String.valueOf(s3*s4)).toString());
                    }
                    if(flag=="/"){
                        tf.setText(s1.append(String.valueOf(s3/s4)).toString());
                    }
                }       

            }
        };
        //添加按钮以及监听器
        JButton bks = new JButton("Backspace");
        bks.addActionListener(listen);
        JButton ce = new JButton("CE");
        ce.addActionListener(listen);
        JButton c = new JButton("C");
        c.addActionListener(listen);
        p2.add(bks);
        p2.add(ce);
        p2.add(c);
        f.add(p2);
        JPanel p3 = new JPanel();
        p3.setLayout(new GridLayout(4,5));
        JButton b1 = new JButton("7");
        p3.add(b1);
        b1.addActionListener(listen);
        JButton b2 = new JButton("8");
        p3.add(b2);
        b2.addActionListener(listen);
        JButton b3 = new JButton("9");
        p3.add(b3);
        b3.addActionListener(listen);
        JButton b4 = new JButton("/");
        p3.add(b4);
        b4.addActionListener(listen);
        JButton b5 = new JButton("sqrt");
        p3.add(b5);
        b5.addActionListener(listen);
        JButton b6 = new JButton("4");
        p3.add(b6);
        b6.addActionListener(listen);
        JButton b7 = new JButton("5");
        p3.add(b7);
        b7.addActionListener(listen);
        JButton b8 = new JButton("6");
        p3.add(b8);
        b8.addActionListener(listen);
        JButton b9 = new JButton("*");
        p3.add(b9);
        b9.addActionListener(listen);
        JButton b10 = new JButton("%");
        p3.add(b10);
        b10.addActionListener(listen);
        JButton b11 = new JButton("1");
        p3.add(b11);
        b11.addActionListener(listen);
        JButton b12 = new JButton("2");
        p3.add(b12);
        b12.addActionListener(listen);
        JButton b13 = new JButton("3");
        p3.add(b13);
        b13.addActionListener(listen);
        JButton b14 = new JButton("-");
        p3.add(b14);
        b14.addActionListener(listen);
        JButton b15 = new JButton("1/x");
        p3.add(b15);
        b15.addActionListener(listen);
        JButton b16 = new JButton("0");
        p3.add(b16);
        b16.addActionListener(listen);
        JButton b17 = new JButton("+/-");
        p3.add(b17);
        b17.addActionListener(listen);
        JButton b18 = new JButton(".");
        p3.add(b18);
        b18.addActionListener(listen);
        JButton b19 = new JButton("+");
        p3.add(b19);
        b19.addActionListener(listen);
        JButton b20 = new JButton("=");
        p3.add(b20);
        b20.addActionListener(listen);
        f.add(p3,BorderLayout.SOUTH);
        f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        f.pack();
        f.setVisible(true);
    }

    public static void main(String args[]){
        //调用方法，实现计算器
        new Cal().init();
    }

}
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package com.lovo.calculator;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
/**
* 计算器类
*
* @author Administrator
*
*/
public class Calculator extends JFrame implements ActionListener {

private static final long serialVersionUID = 3868243398506940702L;

// 文本框
private JTextField result;
// 按钮数组
private JButton[] buttons;
// 按钮文本
private final String[] characters = { "7", "8", "9", "/", "4", "5", "6",
"*", "1", "2", "3", "-", "0", ".", "=", "+" };
// 是否为第一个输入的数字
private boolean isFirstDigit = true;
// 运算结果
private double resultNum = 0.0;
// 运算符
private String operator = "=";
public Calculator(String title) {
// 设置标题栏
super(title);
// 初始化各组件
init();
// 注册各组件监听器
registerListener();
// 显示窗体
setVisible(true);
}
/**
* 初始化各组件
*/
private void init() {
// 常用属性初始化
setSize(220, 200);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
/* 文本框对象初始化 */
result = new JTextField("0");
// 文本右对齐
result.setHorizontalAlignment(JTextField.RIGHT);
// 设置是否可编辑
result.setEditable(false);
/* 按钮初始化 */
buttons = new JButton[characters.length];
for (int i = 0; i < buttons.length; i++) {
buttons[i] = new JButton(characters[i]);
buttons[i].setFocusable(false); // 不允许按钮定位焦点
}
/* 将文本框与按钮添加到窗体中 */
add(result, BorderLayout.NORTH);
JPanel pnl = new JPanel(new GridLayout(4, 4, 5, 5));
for (JButton jButton : buttons) {
pnl.add(jButton);
}
add(pnl);
this.getContentPane().setFocusable(true);
}
/**
* 注册监听器
*/
private void registerListener() {
for (JButton jButton : buttons) {
jButton.addActionListener(this);
}
// 注册键盘事件
this.getContentPane().addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
String text = String.valueOf(e.getKeyChar());
if (Character.isDigit(text.charAt(0)) || ".".equals(text)) { // 数字或小数点
handleNumber(text);
} else if ("+-*/=".indexOf(text) != -1) { // 运算符
handleOperator(text);
} else if (e.getKeyCode() == 8) { // 退格键
String tmp = result.getText().trim();
if (tmp.length() == 1) {
result.setText("0");
isFirstDigit = true;
} else {
result.setText(tmp.substring(0, tmp.length() - 1));
}
}
}
});
}
@Override
public void actionPerformed(ActionEvent e) {
JButton btn = (JButton) e.getSource();
String text = btn.getText().trim();
if (Character.isDigit(text.charAt(0)) || ".".equals(text)) { // 处理数字和小数点
handleNumber(text);
} else { // 处理运算符
handleOperator(text);
}
}
/**
* 处理数字和小数点
*
* @param text
*/
private void handleNumber(String text) {
if (isFirstDigit) { // 第一次输入
if (".".equals(text)) {
this.result.setText("0.");
} else {
this.result.setText(text);
}
} else if ("0".equals(text) && "0".equals(this.result.getText())) {
isFirstDigit = true;
return;
} else if (".".equals(text) && this.result.getText().indexOf(".") == -1) {
this.result.setText(this.result.getText() + ".");
} else if (!".".equals(text)) {
this.result.setText(this.result.getText() + text);
}
isFirstDigit = false;
}
/**
* 处理运算符
*
* @param text
*/
private void handleOperator(String text) {
switch (operator) { // 处理各项运算 适用于JDK1.7版本的
case "+":
resultNum += Double.parseDouble(this.result.getText());
break;
case "-":
resultNum -= Double.parseDouble(this.result.getText());
break;
case "*":
resultNum *= Double.parseDouble(this.result.getText());
break;
case "/":
resultNum /= Double.parseDouble(this.result.getText());
break;
case "=":
resultNum = Double.parseDouble(this.result.getText());
break;
}
// 将文本框的值修改为运算结果
this.result.setText(String.valueOf(resultNum));
// 将点击的运算符放入operator保存
operator = text;
// 下一个数字第一次点击
isFirstDigit = true;
}
}
测试：
package com.lovo.calculator;
public class Test {
public static void main(String[] args) {
new Calculator("My Calculator");
}
}
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布局不是最重要的，重要的是你要理解编程的思想。上面的功能其实很简单吧，不过多新手来说，能做好，说明你的基本功还是不错的
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雨寅08d
2017-11-21 · 超过33用户采纳过TA的回答
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现在很少人用java做图形界面了
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