本程序写于刚刚学习j2se的swing时，记得课堂上老师说起，他们那会儿毕业找工作，能够写出个计算器就算是会写程序的人，就不愁找不到工作了，于是我就写了这个程序，安慰一下失业不久的自己。回想起来，这个东西还是挺能够锻炼逻辑思维的，当初确实是费了不少心思，界面就可以看到，懒这个键是调用Windows系统的计算器，当初就是一步步照它而完成的，当然这个程序并没有实现科学计算。由于程序是刚刚系统学习编程不久时写的，很多地方存在不规范，而且一些地方绕了弯子，诸如界面按钮的定义并不是采用数组而成，而是手工画上去的，再有就是java监听器的使用。
以下为运行效果图：
以下为程序源代码：
package calculate;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
/** *//**
* <p>Title: 简单计算器</p>
*
* <p>Description: </p>
*
* <p>Copyright: Copyright (c) 2007</p>
*
* <p>Company: 无业游民</p>
*
* @author 非凡DZ
* @version 1.0
*/
public class FrameCalculate extends JFrame 
{
private String front = "", behind = ""; //分别用于记录加减乘除运算符之前,之后输入的内容
private String op; //用于记录运算符
private String re;//用于存储运算结果的字符串格式
private boolean flag = false; //用于记录是否按下了运算符
private boolean flag1 = false;//用于判断是否输入了点运算符
private double result;//用于存储运算结果
private boolean flag2 = false;//用于判断是否输入了数字
private boolean flag3 = false;//用于判断是否按下了等号运算符
JPanel contentPane;
JTextField txtResult = new JTextField();
JButton btnNull = new JButton();
JButton btnFour = new JButton();
JButton btnFive = new JButton();
JButton btnSix = new JButton();
JButton btnDecrease = new JButton();
JButton btnBegin = new JButton();
JButton btnOne = new JButton();
JButton btnTwo = new JButton();
JButton btnThree = new JButton();
JButton btnMultiply = new JButton();
JButton btnCancel = new JButton();
JButton btnZero = new JButton();
JButton btnMinus = new JButton();
JButton btnPoint = new JButton();
JButton btnDivide = new JButton();
JButton btnEqual = new JButton();
JButton btnIncrease = new JButton();
JButton btnSeven = new JButton();
JButton btnEight = new JButton();
JButton btnNine = new JButton();
public FrameCalculate() {
try {
setDefaultCloseOperation(EXIT_ON_CLOSE);
jbInit();
} catch (Exception exception) {
exception.printStackTrace();
}
}
/** *//**
* Component initialization.
*
* @throws java.lang.Exception
*/
private void jbInit() throws Exception {
contentPane = (JPanel) getContentPane();
contentPane.setLayout(null);
this.setResizable(false);
setSize(new Dimension(400, 300));
setTitle("计算器");
txtResult.setEnabled(false);
txtResult.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
txtResult.setEditable(false);
txtResult.setText("0");
txtResult.setHorizontalAlignment(SwingConstants.RIGHT);
txtResult.setBounds(new Rectangle(33, 19, 310, 34));
btnNull.setBounds(new Rectangle(298, 70, 46, 37));
btnNull.setFont(new java.awt.Font("Dialog", Font.PLAIN, 12));
btnNull.setText("懒");
btnNull.addActionListener(new FrameCalculate_btnNull_actionAdapter(this));
btnFour.setBounds(new Rectangle(33, 120, 46, 37));
btnFour.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnFour.setText("4");
btnFive.setBounds(new Rectangle(101, 120, 46, 37));
btnFive.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnFive.setText("5");
btnSix.setBounds(new Rectangle(167, 119, 46, 37));
btnSix.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnSix.setText("6");
btnDecrease.setBounds(new Rectangle(234, 120, 46, 37));
btnDecrease.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnDecrease.setText("-");
btnBegin.setBounds(new Rectangle(298, 121, 46, 37));
btnBegin.setFont(new java.awt.Font("Dialog", Font.PLAIN, 15));
btnBegin.setText("C");
btnBegin.addActionListener(new FrameCalculate_btnBegin_actionAdapter(this));
btnOne.setBounds(new Rectangle(33, 172, 46, 37));
btnOne.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnOne.setText("1");
btnTwo.setBounds(new Rectangle(101, 172, 46, 37));
btnTwo.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnTwo.setText("2");
btnThree.setBounds(new Rectangle(167, 172, 46, 37));
btnThree.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnThree.setText("3");
btnMultiply.setBounds(new Rectangle(234, 172, 46, 37));
btnMultiply.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnMultiply.setText("*");
btnCancel.setBounds(new Rectangle(298, 172, 46, 37));
btnCancel.setFont(new java.awt.Font("Dialog", Font.PLAIN, 12));
btnCancel.setText("←");
btnCancel.addActionListener(new FrameCalculate_btnCancel_actionAdapter(this));
btnZero.setBounds(new Rectangle(33, 222, 46, 37));
btnZero.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnZero.setText("0");
//加载数字0-9的监听事件
btnZero.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnOne.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnTwo.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnThree.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnFour.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnFive.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnSix.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnSeven.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnEight.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnNine.addActionListener(new FrameCalculate_btnZero_actionAdapter(this));
btnMinus.setBounds(new Rectangle(101, 222, 46, 37));
btnMinus.setFont(new java.awt.Font("Dialog", Font.PLAIN, 10));
btnMinus.setText("+/-");
btnMinus.addActionListener(new FrameCalculate_btnMinus_actionAdapter(this));
btnPoint.setBounds(new Rectangle(167, 222, 46, 37));
btnPoint.setFont(new java.awt.Font("Dialog", Font.PLAIN, 30));
btnPoint.setHorizontalTextPosition(SwingConstants.CENTER);
btnPoint.setText(".");
btnPoint.addActionListener(new FrameCalculate_btnPoint_actionAdapter(this));
btnDivide.setBounds(new Rectangle(234, 222, 46, 37));
btnDivide.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnDivide.setText("/");
btnEqual.setBounds(new Rectangle(298, 222, 46, 37));
btnEqual.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnEqual.setText("=");
btnEqual.addActionListener(new FrameCalculate_btnEqual_actionAdapter(this));
btnIncrease.setBounds(new Rectangle(234, 70, 46, 37));
btnIncrease.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnIncrease.setText("+");
//加载加减乘除运算符的监听事件
btnIncrease.addActionListener(new
FrameCalculate_btnIncrease_actionAdapter(this));
btnDecrease.addActionListener(new
FrameCalculate_btnIncrease_actionAdapter(this));
btnMultiply.addActionListener(new
FrameCalculate_btnIncrease_actionAdapter(this));
btnDivide.addActionListener(new
FrameCalculate_btnIncrease_actionAdapter(this));
btnSeven.setBounds(new Rectangle(33, 70, 46, 37));
btnSeven.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnSeven.setText("7");
btnEight.setBounds(new Rectangle(101, 70, 46, 37));
btnEight.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnEight.setText("8");
btnNine.setBounds(new Rectangle(167, 70, 46, 37));
btnNine.setFont(new java.awt.Font("Dialog", Font.PLAIN, 20));
btnNine.setText("9");
contentPane.add(btnFive);
contentPane.add(btnSix);
contentPane.add(btnDecrease);
contentPane.add(btnBegin);
contentPane.add(btnOne);
contentPane.add(btnTwo);
contentPane.add(btnThree);
contentPane.add(btnMultiply);
contentPane.add(btnCancel);
contentPane.add(btnMinus);
contentPane.add(btnPoint);
contentPane.add(btnDivide);
contentPane.add(btnEqual);
contentPane.add(btnEight);
contentPane.add(btnNine);
contentPane.add(btnFour);
contentPane.add(btnSeven);
contentPane.add(btnIncrease);
contentPane.add(btnNull);
contentPane.add(txtResult);
contentPane.add(btnZero);
}
public void btnNull_actionPerformed(ActionEvent e) {
try {
Runtime.getRuntime().exec("calc.exe"); //调用系统的计算器
} catch (IOException ex) {
}
}
public void btnZero_actionPerformed(ActionEvent e) {
if (flag) { //如果刚刚按下了运算符
txtResult.setText("");
if (flag1) {//判断之前是否输入了点运算符
txtResult.setText("0." + e.getActionCommand());
flag1 = false;
} else {
txtResult.setText(e.getActionCommand());
}
flag2 = true;
} else {
int num = txtResult.getText().indexOf(".");
if (num < 0 && !txtResult.getText().equals("0")) {
txtResult.setText(txtResult.getText() + e.getActionCommand());
} else if (num < 0 && txtResult.getText().equals("0")) {
txtResult.setText(e.getActionCommand());
} else if (num >= 0 && txtResult.getText().equals("0")) {
txtResult.setText("0." + e.getActionCommand());
} else if (num >= 0 && !txtResult.getText().equals("0")) {
txtResult.setText(txtResult.getText() + e.getActionCommand());
}
}
flag = false;
flag3=false;
}
public void btnIncrease_actionPerformed(ActionEvent e) {
if(flag3){
txtResult.setText(txtResult.getText());
op = e.getActionCommand(); //得到刚刚按下的运算符
front = txtResult.getText(); //记录加减乘除运算符之前输入的内容
}
else if (flag2) {
ActionEvent ee = new ActionEvent("qq", 1, "pp");
btnEqual_actionPerformed(ee);
op = e.getActionCommand(); //得到刚刚按下的运算符
front = re;
flag2 = false;
} else {
front = txtResult.getText(); //记录加减乘除运算符之前输入的内容
op = e.getActionCommand(); //得到刚刚按下的运算符
}
flag3=false;
flag = true; //记录已经按下了加减乘除运算符的其中一个
}
public void btnEqual_actionPerformed(ActionEvent e) {
if(!flag3)//未曾按下等于运算符
behind = txtResult.getText();
else
front = re;
try {
double a1 = Double.parseDouble(front);
double b1 = Double.parseDouble(behind);
if (op == "+") {
result = a1 + b1;
} else if (op == "-") {
result = a1 - b1;
} else if (op == "*") {
result = a1 * b1;
} else {
result = a1 / b1;
}
Double r = new Double(result);
re = r.toString(result);
txtResult.setText(re);
} catch (ArithmeticException ce) {
txtResult.setText("除数不能为零");
} catch (Exception ee) {
}
if (!flag3)
flag3 = true;
}
public void btnPoint_actionPerformed(ActionEvent e) {
int num=txtResult.getText().indexOf(".");
if(num<0 && !flag)
txtResult.setText(txtResult.getText()+e.getActionCommand());
if(flag)
flag1=true;
}
public void btnBegin_actionPerformed(ActionEvent e) {
flag=false;
flag1=false;
flag2=false;
flag3=false;
front="";
behind="";
re="";
txtResult.setText("0");
}
public void btnMinus_actionPerformed(ActionEvent e) {//取反运算符事件处理
if(txtResult.getText().equals("0")){//如果文本框内容为0
txtResult.setText(txtResult.getText());
}else if(txtResult.getText().indexOf("-")>=0){//若文本框中含有负号
String a=txtResult.getText().replaceAll("-","");
txtResult.setText(a);
}else if(flag){
txtResult.setText("0");
}else{
txtResult.setText("-"+txtResult.getText());
}
}
public void btnCancel_actionPerformed(ActionEvent e) {//退格事件处理方法
String str=txtResult.getText();
if(str.length() == 1){//如文本框中只剩下最后一个字符,将文本框内容置为0
txtResult.setText("0");
}
if(str.length()>1){
str=str.substring(0,str.length()-1);
txtResult.setText(str);
}
}
public static void main(String[] args){
FrameCalculate fc = new FrameCalculate();
fc.setSize(400,310);
fc.setLocation(200,150);
fc.setVisible(true);
}
}
class FrameCalculate_btnCancel_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnCancel_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnCancel_actionPerformed(e);
}
}
class FrameCalculate_btnMinus_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnMinus_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnMinus_actionPerformed(e);
}
}
class FrameCalculate_btnBegin_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnBegin_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnBegin_actionPerformed(e);
}
}
class FrameCalculate_btnPoint_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnPoint_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnPoint_actionPerformed(e);
}
}
class FrameCalculate_btnEqual_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnEqual_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnEqual_actionPerformed(e);
}
}
class FrameCalculate_btnIncrease_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnIncrease_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnIncrease_actionPerformed(e);
}
}
class FrameCalculate_btnZero_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnZero_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnZero_actionPerformed(e);
}
}
class FrameCalculate_btnNull_actionAdapter implements ActionListener {
private FrameCalculate adaptee;
FrameCalculate_btnNull_actionAdapter(FrameCalculate adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.btnNull_actionPerformed(e);
}
}