由于刚学JAVA,学个计算器的简单功能都要摆弄半天

特请高手们帮忙

一个计算器的的源代码,只要简单的加减乘除即可
谢谢

学了JButton ActionListener就差不多了 不是交作业就别着急慢慢写 肯定能写出来

给你个例子,研究下
自己写就可以了
import java.awt.*;
import java.lang.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.text.DecimalFormat;
public class Calculator
implements ActionListener { //导入动作监听接口
//设计面板中的单位
JFrame frame;
JTextField textAnswer;
JPanel panel, panel1, panel2, panel3;
JMenuBar mainMenu;
JTextField textMemory;
JLabel labelMemSpace; //labelMemSpace单纯做摆设，控制面板的形状
JButton buttonBk, buttonCe, buttonC;
JButton button[];
JButton buttonMC, buttonMR, buttonMS, buttonMAdd;
JButton buttonDot, buttonAddAndSub, buttonAdd, buttonSub, buttonMul,
buttonDiv, buttonMod;
JButton buttonSqrt, buttonDao, buttonEqual;
JMenu editMenu, viewMenu, helpMenu;
JMenuItem copyItem, pasteItem, tItem, sItem, numberGroup, topHelp, aboutCal;
DecimalFormat df; //设置数据输出精度
boolean clickable; //控制当前能否按键
double memoryd; //使用内存中存储的数字
int memoryi;
double vard, answerd; //用来保存double型数据的中间值(vard)和最后结果(answerd)
short key = -1, prekey = -1; //key用来保存当前进行何种运算,prekey用来保存前次进行何种运算
String copy; //做复制用
JTextArea help; //帮助
JScrollPane scrollHelp;
//构造函数
public Calculator() {
clickable = true;
answerd = 0;
frame = new JFrame("计算器");
df = new DecimalFormat("0.##############"); //设置数据输出精度(对于double型值)
textAnswer = new JTextField(15);
textAnswer.setText("");
textAnswer.setEditable(false);
textAnswer.setBackground(new Color(255, 255, 255));
panel = new JPanel();
frame.getContentPane().add(panel);
panel1 = new JPanel();
panel2 = new JPanel();
panel.setLayout(new BorderLayout());
//设计整个面板
mainMenu = new JMenuBar();
editMenu = new JMenu("编辑(E)");
viewMenu = new JMenu("查看(V)");
helpMenu = new JMenu("帮助(H)");
copyItem = new JMenuItem(" 复制(C) Ctrl+C");
copyItem.addActionListener(this);
pasteItem = new JMenuItem(" 粘贴(V) Ctrl+V");
pasteItem.addActionListener(this);
editMenu.add(copyItem);
editMenu.add(pasteItem);
tItem = new JMenuItem("●标准型(T)");
tItem.addActionListener(this);
sItem = new JMenuItem(" 科学型(S)");
sItem.addActionListener(this);
numberGroup = new JMenuItem(" 数字分组(I)");
numberGroup.addActionListener(this);
viewMenu.add(tItem);
viewMenu.add(sItem);
viewMenu.add(numberGroup);
topHelp = new JMenuItem(" 帮助主题(H)");
topHelp.addActionListener(this);
help = new JTextArea(5, 20);
scrollHelp = new JScrollPane(help);
help.setEditable(false);
help.append("执行简单计算\n");
help.append("1. 键入计算的第一个数字。\n");
help.append("2. 单击“+”执行加、“-”执行减、“*”执行乘或“/”执行除。\n");
help.append("3. 键入计算的下一个数字。\n");
help.append("4. 输入所有剩余的运算符和数字。\n");
help.append("5. 单击“=”。\n");
aboutCal = new JMenuItem(" 关于计算器(A)");
aboutCal.addActionListener(this);
helpMenu.add(topHelp);
helpMenu.add(aboutCal);
mainMenu.add(editMenu);
mainMenu.add(viewMenu);
mainMenu.add(helpMenu);
panel.add(mainMenu, BorderLayout.NORTH);
panel.add(textAnswer, BorderLayout.CENTER);
panel.add(panel1, BorderLayout.SOUTH);
panel1.setLayout(new BorderLayout());
textMemory = new JTextField(3);
textMemory.setEditable(false);
textMemory.setBackground(new Color(217, 217, 217));
labelMemSpace = new JLabel(" ");
buttonBk = new JButton("Backspace");
buttonBk.setForeground(new Color(255, 0, 0));
buttonCe = new JButton("CE");
buttonCe.setForeground(new Color(255, 0, 0));
buttonC = new JButton("C");
buttonC.setForeground(new Color(255, 0, 0));
buttonBk.addActionListener(this);
buttonCe.addActionListener(this);
buttonC.addActionListener(this);
panel1.add(panel2, BorderLayout.NORTH);
panel2.setLayout(new FlowLayout(FlowLayout.RIGHT));
panel2.add(textMemory);
panel2.add(labelMemSpace);
panel2.add(buttonBk);
panel2.add(buttonCe);
panel2.add(buttonC);
panel3 = new JPanel();
panel1.add(panel3, BorderLayout.CENTER);
button = new JButton[10];
for (int i = 0; i < button.length; i++) {
button = new JButton(Integer.toString(i));
button.setForeground(new Color(0, 0, 255));
}
buttonMC = new JButton("MC");
buttonMC.setForeground(new Color(255, 0, 0));
buttonMR = new JButton("MR");
buttonMR.setForeground(new Color(255, 0, 0));
buttonMS = new JButton("MS");
buttonMS.setForeground(new Color(255, 0, 0));
buttonMAdd = new JButton("M+");
buttonMAdd.setForeground(new Color(255, 0, 0));
buttonDot = new JButton(".");
buttonDot.setForeground(new Color(0, 0, 255));
buttonAddAndSub = new JButton("+/-");
buttonAddAndSub.setForeground(new Color(0, 0, 255));
buttonAdd = new JButton("+");
buttonAdd.setForeground(new Color(255, 0, 0));
buttonSub = new JButton("-");
buttonSub.setForeground(new Color(255, 0, 0));
buttonMul = new JButton("*");
buttonMul.setForeground(new Color(255, 0, 0));
buttonDiv = new JButton("/");
buttonDiv.setForeground(new Color(255, 0, 0));
buttonMod = new JButton("%");
buttonMod.setForeground(new Color(0, 0, 255));
buttonSqrt = new JButton("sqrt");
buttonSqrt.setForeground(new Color(0, 0, 255));
buttonDao = new JButton("1/x");
buttonDao.setForeground(new Color(0, 0, 255));
buttonEqual = new JButton("=");
buttonEqual.setForeground(new Color(255, 0, 0));
//将所有行为与监听绑定
panel3.setLayout(new GridLayout(4, 6));
panel3.add(buttonMC);
buttonMC.addActionListener(this);
panel3.add(button[7]);
button[7].addActionListener(this);
panel3.add(button[8]);
button[8].addActionListener(this);
panel3.add(button[9]);
button[9].addActionListener(this);
panel3.add(buttonDiv);
buttonDiv.addActionListener(this);
panel3.add(buttonSqrt);
buttonSqrt.addActionListener(this);
panel3.add(buttonMR);
buttonMR.addActionListener(this);
panel3.add(button[4]);
button[4].addActionListener(this);
panel3.add(button[5]);
button[5].addActionListener(this);
panel3.add(button[6]);
button[6].addActionListener(this);
panel3.add(buttonMul);
buttonMul.addActionListener(this);
panel3.add(buttonMod);
buttonMod.addActionListener(this);
panel3.add(buttonMS);
buttonMS.addActionListener(this);
panel3.add(button[1]);
button[1].addActionListener(this);
panel3.add(button[2]);
button[2].addActionListener(this);
panel3.add(button[3]);
button[3].addActionListener(this);
panel3.add(buttonSub);
buttonSub.addActionListener(this);
panel3.add(buttonDao);
buttonDao.addActionListener(this);
panel3.add(buttonMAdd);
buttonMAdd.addActionListener(this);
panel3.add(button[0]);
button[0].addActionListener(this);
panel3.add(buttonAddAndSub);
buttonAddAndSub.addActionListener(this);
panel3.add(buttonDot);
buttonDot.addActionListener(this);
panel3.add(buttonAdd);
buttonAdd.addActionListener(this);
panel3.add(buttonEqual);
buttonEqual.addActionListener(this);
frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
frame.pack();
frame.show();
}
//设置各个按钮行为
public void actionPerformed(ActionEvent event) {
boolean sign = false; //判断是否是double型数参与运算，是为true，不是为false
Object temp = event.getSource();
try {
//如果按下数据按钮，将按下的按钮代表的数据插入的当前文本框字符串之后
for (int i = 0; i <= 9; i++)
if (temp == button && clickable == true)
textAnswer.setText(textAnswer.getText() + Integer.toString(i));
//按下'.'按钮时，判断当前文本框内字符串中含不含'.'，如果已含，则不允许再插入'.'
if (temp == buttonDot && clickable == true) {
boolean isDot = false;
if (textAnswer.getText().length() == 0)
isDot = true;
for (int i = 0; i < textAnswer.getText().length(); i++)
if ('.' == textAnswer.getText().charAt(i)) {
isDot = true;
break;
}
if (isDot == false)
textAnswer.setText(textAnswer.getText() + ".");
}
if ( (temp == buttonAdd || temp == buttonSub || temp == buttonMul ||
temp == buttonDiv) && clickable == true) {
//'+'操作
if (temp == buttonAdd) {
switch (prekey) {
case 0:
answerd += Double.parseDouble(textAnswer.getText());
break;
case 1:
answerd -= Double.parseDouble(textAnswer.getText());
break;
case 2:
answerd *= Double.parseDouble(textAnswer.getText());
break;
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {
textAnswer.setText("除数不能为零");
clickable = false;
}
else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 0;
}
//'-'操作
if (temp == buttonSub) {
switch (prekey) {
case 0:
answerd += Double.parseDouble(textAnswer.getText());
break;
case 1:
answerd -= Double.parseDouble(textAnswer.getText());
break;
case 2:
answerd *= Double.parseDouble(textAnswer.getText());
break;
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {
textAnswer.setText("除数不能为零");
clickable = false;
}
else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 1;
}
//'*'操作
if (temp == buttonMul) {
switch (prekey) {
case 0:
answerd += Double.parseDouble(textAnswer.getText());
break;
case 1:
answerd -= Double.parseDouble(textAnswer.getText());
break;
case 2:
answerd *= Double.parseDouble(textAnswer.getText());
break;
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {
textAnswer.setText("除数不能为零");
clickable = false;
}
else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 2;
}
//'/'操作
if (temp == buttonDiv) {
switch (prekey) {
case 0:
answerd += Double.parseDouble(textAnswer.getText());
break;
case 1:
answerd -= Double.parseDouble(textAnswer.getText());
break;
case 2:
answerd *= Double.parseDouble(textAnswer.getText());
break;
case 3:
if (Double.parseDouble(textAnswer.getText()) == 0) {
textAnswer.setText("除数不能为零");
clickable = false;
}
else
answerd /= Double.parseDouble(textAnswer.getText());
break;
default:
answerd = Double.parseDouble(textAnswer.getText());
}
textAnswer.setText("");
prekey = key = 3;
}
}
//'='操作
if (temp == buttonEqual && clickable == true) {
//如果连续按'=',则进行连续运算
if (prekey == 5) {
if (key == 0) {
answerd += vard;
textAnswer.setText(df.format(answerd));
}
if (key == 1) {
answerd -= vard;
textAnswer.setText(df.format(answerd));
}
if (key == 2) {
answerd *= vard;
textAnswer.setText(df.format(answerd));
}
if (key == 3) {
if (Double.parseDouble(textAnswer.getText()) == 0) {
textAnswer.setText("除数不能为零");
clickable = false;
}
else {
answerd /= vard;
textAnswer.setText(df.format(answerd));
}
}
}
else {
vard = Double.parseDouble(textAnswer.getText());
if (key == 0) {
prekey = -1;
answerd += Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
if (key == 1) {
prekey = -1;
answerd -= Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
if (key == 2) {
prekey = -1;
answerd *= Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
if (key == 3) {
prekey = -1;
if (Double.parseDouble(textAnswer.getText()) == 0) {
textAnswer.setText("除数不能为零");
clickable = false;
}
else {
answerd /= Double.parseDouble(textAnswer.getText());
textAnswer.setText(df.format(answerd));
}
}
}
prekey = 5;
}
//'%'操作，对第二个操作数除以100
if (temp == buttonMod && clickable == true) {
if (answerd == 0) {
String s = textAnswer.getText();
textAnswer.setText(s);
}
else {
boolean isDot = false;
for (int i = 0; i < textAnswer.getText().length(); i++)
if ('.' == textAnswer.getText().charAt(i)) {
isDot = true;
break;
}
//如果是double数，除100
if (isDot == true) {
double dtemp = Double.parseDouble(textAnswer.getText());
dtemp = dtemp / 100.0;
textAnswer.setText(Double.toString(dtemp));
}
else {
//如果是int数但能被100整除，则去掉末尾两个零
if (Integer.parseInt(textAnswer.getText()) % 100 == 0) {
int itemp = Integer.parseInt(textAnswer.getText());
itemp /= 100;
textAnswer.setText(Integer.toString(itemp));
}
//如果是int数，但不能被100整除，则按double数处理
else {
double dtemp = Double.parseDouble(textAnswer.getText());
dtemp = dtemp / 100.0;
textAnswer.setText(Double.toString(dtemp));
}
}
}
}
//开根号运算
if (temp == buttonSqrt && clickable == true) {
String s = textAnswer.getText();
if (s.charAt(0) == '-') {
textAnswer.setText("负数不能开根号");
clickable = false;
}
else
textAnswer.setText(Double.toString(java.lang.Math.sqrt(Double.
parseDouble(textAnswer.getText()))));
}
//倒数运算
if (temp == buttonDao && clickable == true) {
if (textAnswer.getText().charAt(0) == '0' &&
textAnswer.getText().length() == 1) {
textAnswer.setText("零不能求倒数");
clickable = false;
}
else {
boolean isDec = true;
int i, j, k;
String s = Double.toString(1 / Double.parseDouble(textAnswer.getText()));
for (i = 0; i < s.length(); i++)
if (s.charAt(i) == '.')
break;
for (j = i + 1; j < s.length(); j++)
if (s.charAt(j) != '0') {
isDec = false;
break;
}
if (isDec == true) {
String stemp = "";
for (k = 0; k < i; k++)
stemp += s.charAt(k);
textAnswer.setText(stemp);
}
else
textAnswer.setText(s);
}
}
//按下'+/-'按钮时处理
if (temp == buttonAddAndSub && clickable == true) {
boolean isNumber = true;
String s = textAnswer.getText();
for (int i = 0; i < s.length(); i++)
if (! (s.charAt(i) >= '0' && s.charAt(i) <= '9' || s.charAt(i) == '.' ||
s.charAt(i) == '-')) {
isNumber = false;
break;
}
if (isNumber == true) {
//如果当前字符串首字母有'-'号,代表现在是个负数,再按下时,则将首符号去掉
if (s.charAt(0) == '-') {
textAnswer.setText("");
for (int i = 1; i < s.length(); i++) {
char a = s.charAt(i);
textAnswer.setText(textAnswer.getText() + a);
}
}
//如果当前字符串第一个字符不是符号，则添加一个符号在首字母处
else
textAnswer.setText('-' + s);
}
}
//计算器有关内存操作
//'MC'的操作，将内存清0
if (temp == buttonMC && clickable == true) {
memoryd = memoryi = 0;
textMemory.setText("");
}
//'MS'的操作，将当前文本框内容保存入内存，显示'M'
if (temp == buttonMS && clickable == true) {
boolean isDot = false;
textMemory.setText(" M");
for (int i = 0; i < textAnswer.getText().length(); i++)
if ('.' == textAnswer.getText().charAt(i)) {
isDot = true;
break;
}
//如果是double,则存入memoryd(double存储器)
if (isDot == true) {
memoryd = Double.parseDouble(textAnswer.getText());
memoryi = 0; //保证存储器中存放最新的值
}
//如果是int,则存入memoryi(int存储器)
else {
memoryi = Integer.parseInt(textAnswer.getText());
memoryd = 0; //保证存储器中存放最新的值
}
}
//'MR'的操作，将存储器中的信息输出
if (temp == buttonMR && clickable == true) {
if (memoryd != 0)
textAnswer.setText(Double.toString(memoryd));
if (memoryi != 0)
textAnswer.setText(Integer.toString(memoryi));
}
//'M+'的功能，将当前文本框里的数据和存储器中数据相加后，再存入存储器
if (temp == buttonMAdd && clickable == true) {
boolean isDot = false;
for (int i = 0; i < textAnswer.getText().length(); i++)
if ('.' == textAnswer.getText().charAt(i)) {
isDot = true;
break;
}
if (memoryi != 0) { //存储中是一个int型数
if (isDot == false) //被加数是一个int型数
memoryi += Integer.parseInt(textAnswer.getText());
else { //被加数是一个double型数，则将int存储器中数传入double存储器与当前数相加，int存储器清零
memoryd = memoryi + Double.parseDouble(textAnswer.getText());
memoryi = 0;
}
}
else
memoryd += Double.parseDouble(textAnswer.getText());
}
//按下'Backspace'键，利用循环将当前字符串中的最后一个字母删除
if (temp == buttonBk && clickable == true) {
String s = textAnswer.getText();
textAnswer.setText("");
for (int i = 0; i < s.length() - 1; i++) {
char a = s.charAt(i);
textAnswer.setText(textAnswer.getText() + a);
}
}
//按下'CE'按钮，将当前文本框内数据清除
if (temp == buttonCe) {
textAnswer.setText("");
clickable = true;
}
//按下'C'按钮，文本框内数据清除，同时var,answer清0
if (temp == buttonC) {
vard = answerd = 0;
textAnswer.setText("");
clickable = true;
}
//按下'复制'菜单栏
if (temp == copyItem) {
copy = textAnswer.getText();
}
//按下'粘贴'菜单栏
if (temp == pasteItem) {
textAnswer.setText(copy);
}
if (temp == sItem) {
JOptionPane.showMessageDialog(panel, "当前是标准型计算器，\n科学型计算器有待更新。");
}
//按下'帮助主题'菜单栏
if (temp == topHelp) {
JOptionPane.showMessageDialog(panel, scrollHelp);
}
//按下'数字分组'菜单栏
if (temp == numberGroup) {
if (numberGroup.getText().compareTo(" 数字分组(I)") == 0)
numberGroup.setText("√数字分组(I)");
else
numberGroup.setText(" 数字分组(I)");
}
//按下'关于'菜单栏
if (temp == aboutCal) {
JOptionPane.showMessageDialog(panel, "计算器1.00版\n开发者：楼竞");
}
}
//输入中如果有操作非法，比如按下两次'+'，捕获异常
catch (Exception e) {
textAnswer.setText("操作非法");
clickable = false;
}
}
//主函数
public static void main(String args[]) {
new Calculator();
}
}

你这例子 好长啊  

这个功能简单 容易看 呵呵
import java.awt.*;
import java.awt.event.*;
public class Calculator extends Frame
{
TextField text = new TextField(20);
Panel p=new Panel();
double num; //存放操作数
String op;
double result; //存放计算结果
int idx=0; //用于退格键
boolean flag=false;//用于追加数字还是重新显示
boolean dbClick=false;//是否连按"="号
public Calculator()
{
super("简易计算器");
String[] name ={"退格","CE","C","/","7","8","9","*","4","5","6","-",
"1","2","3","+","0","+/-",".","="};
Button[] button= new Button[name.length];
add(text,"North");
text.setFont(new Font("宋体",Font.BOLD,20));
text.setText("0.0");
text.setEditable(false);
text.setFocusable(false);

p.setLayout(new GridLayout(5,4,2,2));
for (int i=0;i<name.length;i++)
{
button[i]=new Button(name[i]);
if(i<=3||i==7||i==11||i==15||i==19)
{//设置按钮前景色
button[i].setForeground(Color.red);
}
else
{
button[i].setForeground(Color.blue);
}
button[i].setFont(new Font("宋体",Font.BOLD,15));
button[i].addActionListener(new MyActionListener());//添加监听器
p.add(button[i]);
}
add(p,"South");
setSize(250,200);
this.setLocation(300,300);
this.setResizable(false);//窗体不可改变大小
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
this.setVisible(true);
}
class MyActionListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String input=text.getText();
String str=e.getActionCommand();
if(isNum(str))
{
if(!flag)
{
if(input!=""&&!input.equals("0.0")&&!input.equals("0"))
{
text.setText(input+str);
}
else
{
text.setText(str);
}
}
else
{
text.setText(str);
}
flag=false;
}
else if(str.equals("+")||str.equals("-")||str.equals("*")||str.equals("/"))
{
result=Double.parseDouble(input);
op=str;
flag=true;
dbClick=false;
}
if(str.equals("="))
{
if(dbClick==false)
{
num=Double.parseDouble(input);
}
if(op.equals("+"))
{
result+=num;
}
if(op.equals("-"))
{
result-=num;
}
if(op.equals("*"))
{
result*=num;
}
if(op.equals("/"))
{
if(num!=0.0)
{
result/=num;
}
}
text.setText(""+result);
flag=false;
dbClick=true;
}
if(str.equals("CE"))
{
text.setText("0.0");
num=0;
}
if(str.equals(".")&&input.indexOf(".")<0)
{
text.setText(input+".");
}
if(str.equals("+/-"))
{
double m = Double.parseDouble(input);
if(m!=0.0)
{
text.setText(m*(-1)+"");
}
}
if(str.equals("C"))
{
text.setText("0.0");
flag=false;
dbClick=false;
result=0;
num=0;
}
if(str.equals("退格"))
{
idx=input.length()-1;
if(idx<0)
{
return;
}
text.setText(input.substring(0,idx));
}

}
}
public boolean isNum(String str)
{
if(str.equals("0")||str.equals("1")||str.equals("2")||str.equals("3")||str.equals("4")
||str.equals("5")||str.equals("6")||str.equals("7")||str.equals("8")||str.equals("9"))
{
return true;
}
else
{
return false;
}
}
public static void main(String[] args)
{
new Calculator();
}
}