计算器java代码实现 java编写简单计算器代码
如何用JAVA语言编写计算器小程序？
具体代码如下：
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import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class Calculator extends JFrame implements ActionListener {
private JFrame jf;
private JButton[] allButtons;
private JButton clearButton;
private JTextField jtf;
public Calculator() {
//对图形组件实例化
jf=new JFrame("任静的计算器1.0：JAVA版");
jf.addWindowListener(new WindowAdapter(){
public void windowClosing(){
System.exit(0);
}
});
allButtons=new JButton[16];
clearButton=new JButton("清除");
jtf=new JTextField(25);
jtf.setEditable(false);
String str="123+456-789*0.=/";
for(int i=0;iallButtons.length;i++){
allButtons[i]=new JButton(str.substring(i,i+1));
}
}
public void init(){
//完成布局
jf.setLayout(new BorderLayout());
JPanel northPanel=new JPanel();
JPanel centerPanel=new JPanel();
JPanel southPanel=new JPanel();
northPanel.setLayout(new FlowLayout());
centerPanel.setLayout(new GridLayout(4,4));
southPanel.setLayout(new FlowLayout());
northPanel.add(jtf);
for(int i=0;i16;i++){
centerPanel.add(allButtons[i]);
}
southPanel.add(clearButton);
jf.add(northPanel,BorderLayout.NORTH);
jf.add(centerPanel,BorderLayout.CENTER);
jf.add(southPanel,BorderLayout.SOUTH);
addEventHandler();
}
//添加事件监听
public void addEventHandler(){
jtf.addActionListener(this);
for(int i=0;iallButtons.length;i++){
allButtons[i].addActionListener(this);
}
clearButton.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
Calculator.this.jtf.setText("");
}
});
}
//事件处理
public void actionPerformed(ActionEvent e) {
//在这里完成事件处理 使计算器可以运行
String action=e.getActionCommand();
if(action=="+"||action=="-"||action=="*"||action=="/"){
}
}
public void setFontAndColor(){
Font f=new Font("宋体",Font.BOLD,24);
jtf.setFont(f);
jtf.setBackground(new Color(0x8f,0xa0,0xfb));
for(int i=0;i16;i++){
allButtons[i].setFont(f);
allButtons[i].setForeground(Color.RED);
}
}
public void showMe(){
init();
setFontAndColor();
jf.pack();
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args){
new Calculator().showMe();
}
}
用JAVA编写一个计算器
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
public class Jisuanqi extends JFrame implements ActionListener {
/**
*
*/
private static final long serialVersionUID = 1L;
Result result = new Result(); // 定义text的面板
Number_Key number_key = new Number_Key(); // 定义按钮面板
// 当点击按钮+、-、*、/时，com = true
boolean com = false;
// 当i=0时说明是我们第一次输入，字符串text不会累加
int i = 0;
// 存放text的内容
String text = "";
// 存放点击按钮+、-、*、/之前的数值
double defbutton = 0;
// +、-、*、/的代号分别为1，2，3，4
int symbol = 0;
// 构造函数
Jisuanqi() {
super("WangJiao"); // 设定标题
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 设定关闭窗体时退出程序
JPanel pane = new JPanel(); // 定义主面板
pane.setLayout(new BorderLayout());
setBounds(380, 220, 30, 80); // 前两个参数是在屏幕上显示的坐标，后两个是大小
// 替换图标
ImageIcon icon = new ImageIcon("F:1.GIF");
// Jisuanqi.class.getResource("APPLE.GIF")
// );
setIconImage(icon.getImage());
pane.add(result, BorderLayout.NORTH);
pane.add(number_key, BorderLayout.CENTER);
pane.add(number_key.equal, BorderLayout.SOUTH);
number_key.one.addActionListener(this); // 对1按钮添加监听事件
number_key.two.addActionListener(this); // 对2按钮添加监听事件
number_key.three.addActionListener(this); // 对3按钮添加监听事件
number_key.four.addActionListener(this); // 对4按钮添加监听事件
number_key.five.addActionListener(this); // 对5按钮添加监听事件
number_key.six.addActionListener(this); // 对6按钮添加监听事件
number_key.seven.addActionListener(this); // 对7按钮添加监听事件
number_key.eight.addActionListener(this); // 对8按钮添加监听事件
number_key.nine.addActionListener(this); // 对9按钮添加监听事件
number_key.zero.addActionListener(this); // 对0按钮添加监听事件
number_key.ce.addActionListener(this); // 对置零按钮添加监听事件
number_key.plus.addActionListener(this); // 对+按钮添加监听事件
number_key.equal.addActionListener(this); // 对=按钮添加监听事件
number_key.sub.addActionListener(this); // 对-按钮添加监听事件
number_key.mul.addActionListener(this); // 对*按钮添加监听事件
number_key.div.addActionListener(this); // 对/按钮添加监听事件
number_key.point.addActionListener(this); // 对.按钮添加监听事件
setContentPane(pane);
pack(); // 初始化窗体大小为正好盛放所有按钮
}
// 各个按钮触发的事件
public void actionPerformed(ActionEvent e) {
/*
* 如果是点击数字按钮那么先要判断是否在此之前点击了+、-、*、/、=，如果是那么com=true 如果没有com=
* false;或者是否点击数字键，如果是i = 1,如果没有 i = 0;
*/
if (e.getSource() == number_key.one) {
if (com || i == 0) {
result.text.setText("1");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "1");
}
} else if (e.getSource() == number_key.two) {
if (com || i == 0) {
result.text.setText("2");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "2");
}
} else if (e.getSource() == number_key.three) {
if (com || i == 0) {
result.text.setText("3");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "3");
}
} else if (e.getSource() == number_key.four) {
if (com || i == 0) {
result.text.setText("4");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "4");
}
} else if (e.getSource() == number_key.five) {
if (com || i == 0) {
result.text.setText("5");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "5");
}
} else if (e.getSource() == number_key.six) {
if (com || i == 0) {
result.text.setText("6");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "6");
}
} else if (e.getSource() == number_key.seven) {
if (com || i == 0) {
result.text.setText("7");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "7");
}
} else if (e.getSource() == number_key.eight) {
if (com || i == 0) {
result.text.setText("8");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "8");
}
} else if (e.getSource() == number_key.nine) {
if (com || i == 0) {
result.text.setText("9");
com = false;
i = 1;
} else {
text = result.text.getText();
result.text.setText(text + "9");
}
}
/*
* 对于0这个按钮有一定的说法，在我的程序里不会出现如00000这样的情况，我加了判断条件就是
* 如果text中的数值=0就要判断在这个数值中是否有.存在?如果有那么就在原来数值基础之上添 加0;否则保持原来的数值不变
*/
else if (e.getSource() == number_key.zero) { // result.text.getText()是得到text里内容的意思
if (com || i == 0) {
result.text.setText("0");
com = false;
i = 1;
} else {
text = result.text.getText();
if (Float.parseFloat(text) 0 || Float.parseFloat(text) 0) { // Float.parseFloat(text)就是类型转换了，下面都是一样
result.text.setText(text + "0");
} else {
if (text.trim().indexOf(".") == -1) {
result.text.setText(text);
} else {
result.text.setText(text + "0");
}
}
}
} else if (e.getSource() == number_key.ce) {
result.text.setText("0");
i = 0;
com = true;
// text = "";
defbutton = 0;
}
/*
* 本程序不会让一个数值中出现2个以上的小数点.具体做法是:判断是否已经存在.存在就不添加, 不存在就添加.
*/
else if (e.getSource() == number_key.point) {
if (com || i == 0) {
result.text.setText("0.");
com = false;
i = 1;
} else {
text = result.text.getText();
if (text.trim().indexOf(".") == -1) {
result.text.setText(text + ".");
} else {
result.text.setText(text);
}
}
} // 获得点击+之前的数值
else if (e.getSource() == number_key.plus) {
com = true;
i = 0;
defbutton = Double.parseDouble(result.text.getText());
symbol = 1;
} // 获得点击-之前的数值
else if (e.getSource() == number_key.sub) {
com = true;
i = 0;
defbutton = Double.parseDouble(result.text.getText());
symbol = 2;
} // 获得点击*之前的数值
else if (e.getSource() == number_key.mul) {
com = true;
i = 0;
defbutton = Double.parseDouble(result.text.getText());
System.out.println(defbutton);
symbol = 3;
} // 获得点击/之前的数值
else if (e.getSource() == number_key.div) {
com = true;
i = 0;
defbutton = Double.parseDouble(result.text.getText());
symbol = 4;
} else if (e.getSource() == number_key.equal) {
switch (symbol) {
case 1: { // 计算加法
double ad = defbutton
+ Double.parseDouble(result.text.getText());
result.text.setText(ad + "");
i = 0;
text = "";
break;
}
case 2: { // 计算减法
double ad = defbutton
- Double.parseDouble(result.text.getText());
result.text.setText(String.valueOf(ad));
i = 0;
text = "";
break;
}
case 3: { // 计算乘法
double ad = defbutton
* Double.parseDouble(result.text.getText());
result.text.setText(ad + "");
i = 0;
text = "";
break;
}
case 4: { // 计算除法
double ad = defbutton
/ Double.parseDouble(result.text.getText());
result.text.setText(ad + "");
i = 0;
text = "";
break;
}
}
System.out.println(com);
}
System.out.println(result.text.getText());
}
@SuppressWarnings("deprecation")
public static void main(String[] args) {
Jisuanqi loveyou = new Jisuanqi();
loveyou.show();
}
}
// 计算器数字按钮定义面板
class Number_Key extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
JButton zero = new JButton("0"); // 数字键0
JButton one = new JButton("1"); // 数字键1
JButton two = new JButton("2"); // 数字键2
JButton three = new JButton("3"); // 数字键3
JButton four = new JButton("4"); // 数字键4
JButton five = new JButton("5"); // 数字键5
JButton six = new JButton("6"); // 数字键6
JButton seven = new JButton("7"); // 数字键7
JButton eight = new JButton("8"); // 数字键8
JButton nine = new JButton("9"); // 数字键9
JButton plus = new JButton("+");
JButton sub = new JButton("-");
JButton mul = new JButton("*");
JButton div = new JButton("/");
JButton equal = new JButton("=");
JButton ce = new JButton("清零"); // 置零键
JButton point = new JButton(".");
Number_Key() {
setLayout(new GridLayout(4, 4, 1, 1)); // 定义布局管理器为网格布局
setBackground(Color.blue); // 设置背景颜色
// 添加按钮
add(one);
add(two);
add(three);
add(four);
add(five);
add(six);
add(seven);
add(eight);
add(nine);
add(zero);
add(plus);
add(sub);
add(mul);
add(div);
add(point);
add(equal);
add(ce);
}
}
// 计算器显示结果的窗体
class Result extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
// text先是输入和结果
JTextField text = new JTextField("0");
@SuppressWarnings("deprecation")
Result() { // 讲输入的数字或得到的结果在text的右边显示
text.setHorizontalAlignment(SwingConstants.RIGHT);
text.enable(false); // 文本框不能编辑
setLayout(new BorderLayout()); // 设定布局管理器边框布局
add(text, BorderLayout.CENTER); // text放置在窗体的中间
}
}
直接复制 保存成Jisuanqi .java可以直接运行了
求用JAVA实现计算器的代码（可实用的，没语法错误的）
import java.awt.BorderLayout; import java.awt.Color; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JTextField; import javax.swing.border.TitledBorder; //导包 public class Jisuanqi extends JFrame implements ActionListener { //继承JFrame 实现事件监听 private JTextField reasult; private JButton btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btn0, btnAC, btnAdd, btnSub, btnReasult, btnD, btnAbout, btnCancel; private boolean add, sub, end, s, c; private String str; private double num1, num2; public Jisuanqi() { //构造属性 JPanel p1 = new JPanel(); JPanel p2 = new JPanel(); JPanel p3 = new JPanel(); TitledBorder tb = new TitledBorder("输出"); tb.setTitleColor(Color.BLUE); //标题边框底端线 设置颜色 btnAbout = new JButton(" 关于 "); btnCancel = new JButton("Cancel"); //两个按钮 btnCancel.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ee) { System.exit(0); } }); //给Cancel添加事件监听 当鼠标点击时 程序结束 btnAbout.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ee) { JOptionPane.showMessageDialog(null, "黄盖！！", "消息", JOptionPane.INFORMATION_MESSAGE); } //给“关于”添加事件监听 当鼠标点击时 弹出对话框 显示黄盖 }); p3.add(btnAbout); p3.add(btnCancel); // JPanel p4=new JPanel(); // JPanel p5=new JPanel(); // reasult.setBorder(tb); reasult = new JTextField("0", 20); reasult.setEditable(false); //设置不能修改 reasult.setHorizontalAlignment(JTextField.RIGHT); // 设置文本的水平对齐方式。 reasult.setForeground(Color.BLUE); //颜色 p1.setBorder(tb); p1.add(reasult); btn0 = new JButton("0"); btn0.addActionListener(this); btn1 = new JButton("1"); btn1.addActionListener(this); btn2 = new JButton("2"); btn2.addActionListener(this); btn3 = new JButton("3"); btn3.addActionListener(this); btn4 = new JButton("4"); btn4.addActionListener(this); btn5 = new JButton("5"); btn5.addActionListener(this); btn6 = new JButton("6"); btn6.addActionListener(this); btn7 = new JButton("7"); btn7.addActionListener(this); btn8 = new JButton("8"); btn8.addActionListener(this); btn9 = new JButton("9"); btn9.addActionListener(this); btnD = new JButton("."); btnD.addActionListener(this); btnD.setForeground(Color.RED); btnAC = new JButton("AC"); btnAC.addActionListener(this); btnAC.setBackground(Color.PINK); btnAdd = new JButton("+"); btnAdd.addActionListener(this); btnAdd.setForeground(Color.BLUE); btnSub = new JButton("—"); btnSub.addActionListener(this); btnSub.setForeground(Color.BLUE); btnReasult = new JButton("="); btnReasult.addActionListener(this); btnReasult.setForeground(Color.RED); //事件监听 + 颜色 p2.add(btn1); p2.add(btn2); p2.add(btn3); p2.add(btn4); p2.add(btn5); p2.add(btn6); p2.add(btn7); p2.add(btn8); p2.add(btn9); p2.add(btn0); p2.add(btnD); p2.add(btnAC); p2.add(btnAdd); p2.add(btnSub); p2.add(btnReasult); //面板上添加按钮 p2.setLayout(new GridLayout(5, 3)); //面板上设置对齐方式 add(p1, BorderLayout.NORTH); add(p2, BorderLayout.CENTER); add(p3, BorderLayout.SOUTH); //将p1 p2 p3 面板对象添加到JFrame } public void num(int i) { String s = null; s = String.valueOf(i); if (end) { // 如果数字输入结束，则将文本框置零，重新输入 reasult.setText("0"); end = false; } if ((reasult.getText()).equals("0")) { // 如果文本框的内容为零，则覆盖文本框的内容 reasult.setText(s); } else { // 如果文本框的内容不为零，则在内容后面添加数字 str = reasult.getText() + s; reasult.setText(str); } }/* * * String s=null; * * s=String.valueOf(i); * * str=reasult.getText()+s; * * reasult.setText(str); * * } */ public void actionPerformed(ActionEvent e) { if (e.getSource() == btn1) num(1); else if (e.getSource() == btn2) num(2); else if (e.getSource() == btn3) num(3); else if (e.getSource() == btn4) num(4); else if (e.getSource() == btn5) num(5); else if (e.getSource() == btn6) num(6); else if (e.getSource() == btn7) num(7); else if (e.getSource() == btn8) num(8); else if (e.getSource() == btn9) num(9); else if (e.getSource() == btn0) num(0); else if (e.getSource() == btnAdd) { sign(1); btnD.setEnabled(true); } else if (e.getSource() == btnSub) { sign(2); btnD.setEnabled(true); } else if (e.getSource() == btnAC) { btnD.setEnabled(true); reasult.setText("0"); } else if (e.getSource() == btnD) { str = reasult.getText(); str += "."; reasult.setText(str); btnD.setEnabled(false); } else if (e.getSource() == btnReasult) { btnD.setEnabled(true); num2 = Double.parseDouble(reasult.getText()); if (add) { num1 = num1 + num2; } else if (sub) { num1 = num1 - num2; } reasult.setText(String.valueOf(num1)); end = true; } } public void sign(int s) { if (s == 1) { add = true; sub = false; } else if (s == 2) { add = false; sub = true; } num1 = Double.parseDouble(reasult.getText()); end = true; } //设计计算的过程 public static void main(String[] args) { Jisuanqi j = new Jisuanqi(); j.setTitle("+/-简易计算器"); j.setLocation(500, 280); j.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //默认关闭可以关闭程序 j.setResizable(false); j.pack(); j.setVisible(true); } } 这个计算机，绝对让你满意
JAVA简单咋做，计算器代码
简单写了下，代码如下请参照：
/**
* 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;
}
public static void main(String[] args) {
new Calculator("My Calculator");
}
}
运行结果如下：
用java实现一个简单的计算器。
/*
* @(#)JCalculator.java 1.00 06/17/2015
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
* A simple calculator program.
* pI saw this program in a QQ group, and help a friend correct it./p
*
* @author Singyuen Yip
* @version 1.00 12/29/2009
* @see JFrame
* @see ActionListener
*/
public class JCalculator extends JFrame implements ActionListener {
/**
* Serial Version UID
*/
private static final long serialVersionUID = -169068472193786457L;
/**
* This class help close the Window.
* @author Singyuen Yip
*
*/
private class WindowCloser extends WindowAdapter {
public void windowClosing(WindowEvent we) {
System.exit(0);
}
}
int i;
// Strings for Digit Operator buttons.
private final String[] str = { "7", "8", "9", "/", "4", "5", "6", "*","1",
"2", "3", "-", ".", "0", "=", "+" };
// Build buttons.
JButton[] buttons = new JButton[str.length];
// For cancel or reset.
JButton reset = new JButton("CE");
// Build the text field to show the result.
JTextField display = new JTextField("0");
/**
* Constructor without parameters.
*/
public JCalculator() {
super("Calculator");
// Add a panel.
JPanel panel1 = new JPanel(new GridLayout(4, 4));
// panel1.setLayout(new GridLayout(4,4));
for (i = 0; i str.length; i++) {
buttons[i] = new JButton(str[i]);
panel1.add(buttons[i]);
}
JPanel panel2 = new JPanel(new BorderLayout());
// panel2.setLayout(new BorderLayout());
panel2.add("Center", display);
panel2.add("East", reset);
// JPanel panel3 = new Panel();
getContentPane().setLayout(new BorderLayout());
getContentPane().add("North", panel2);
getContentPane().add("Center", panel1);
// Add action listener for each digit operator button.
for (i = 0; i str.length; i++)
buttons[i].addActionListener(this);
// Add listener for "reset" button.
reset.addActionListener(this);
// Add listener for "display" button.
display.addActionListener(this);
// The "close" button "X".
addWindowListener(new WindowCloser());
// Initialize the window size.
setSize(800, 800);
// Show the window.
// show(); Using show() while JDK version is below 1.5.
setVisible(true);
// Fit the certain size.
pack();
}
public void actionPerformed(ActionEvent e) {
Object target = e.getSource();
String label = e.getActionCommand();
if (target == reset)
handleReset();
else if ("0123456789.".indexOf(label) 0)
handleNumber(label);
else
handleOperator(label);
}
// Is the first digit pressed?
boolean isFirstDigit = true;
/**
* Number handling.
* @param key the key of the button.
*/
public void handleNumber(String key) {
if (isFirstDigit)
display.setText(key);
else if ((key.equals(".")) (display.getText().indexOf(".") 0))
display.setText(display.getText() + ".");
else if (!key.equals("."))
display.setText(display.getText() + key);
isFirstDigit = false;
}
/**
* Reset the calculator.
*/
public void handleReset() {
display.setText("0");
isFirstDigit = true;
operator = "=";
}
double number = 0.0;
String operator = "=";
/**
* Handling the operation.
* @param key pressed operator's key.
*/
public void handleOperator(String key) {
if (operator.equals("+"))
number += Double.valueOf(display.getText());
else if (operator.equals("-"))
number -= Double.valueOf(display.getText());
else if (operator.equals("*"))
number *= Double.valueOf(display.getText());
else if (operator.equals("/"))
number /= Double.valueOf(display.getText());
else if (operator.equals("="))
number = Double.valueOf(display.getText());
display.setText(String.valueOf(number));
operator = key;
isFirstDigit = true;
}
public static void main(String[] args) {
new JCalculator();
}
}
运行界面：
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