import java.awt.*;
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import java.applet.*;
public class CalculatorDemo extends Applet
{
TextField answerText;
Button pointButton,equalButton,plusButton;
Button minusButton,clearButton,multiButton,divisionButton;
Button[] b=new Button[10];
String currentOp,preOp;
String foreText,backText;
boolean isFloat=false;
public void init()
{
Panel p1=new Panel();
Panel p2=new Panel();
Panel p3=new Panel();
currentOp=new String("");
preOp=new String("");
foreText=new String("");
backText=new String("");
answerText=new TextField(8);
setBackground(Color.lightGray);
setForeground(Color.blue);
for(int i=9;i=0;i--)
{
b[i]=new Button(Integer.toString(i));
p2.add(b[i]);
}
pointButton=new Button(".");
equalButton=new Button("=");
equalButton.setForeground(Color.red);
clearButton=new Button("清除");
clearButton.setForeground(Color.red);
divisionButton=new Button("/");
divisionButton.setForeground(Color.red);
multiButton=new Button("*");
multiButton.setForeground(Color.red);
minusButton=new Button("-");
minusButton.setForeground(Color.red);
plusButton=new Button("+");
plusButton.setForeground(Color.red);
setLayout(new FlowLayout());
p1.setLayout(new FlowLayout());
p2.setLayout(new GridLayout(4,3));
p3.setLayout(new GridLayout(4,1));
p1.add(answerText);
p1.add(clearButton);
p2.add(pointButton);
p2.add(equalButton);
p3.add(plusButton);
p3.add(minusButton);
p3.add(multiButton);
p3.add(divisionButton);
add(p1);
add(p2);
add(p3);
}
public boolean action(Event e,Object o)
{
String s=new String("");
for(int i=0;i10;i++)
{
if(e.target==b[i]||e.target==pointButton)
{
if(e.target !=pointButton)
{
s=(String)o;
doForeText(s);
}
if((e.target==pointButton)(!isFloat))
{
isFloat=true;
s=(String)o;
if(foreText.equals(""))
{
foreText +="0.";
}
else
{
doForeText(s);
}
}
}
}
if(e.target==clearButton)
{
doClear();
}
if((e.target==clearButton)||(e.target==divisionButton)
||(e.target==plusButton)||(e.target==minusButton))
{
if(foreText !="")
{
currentOp=((String)o);
doOperator();
}
else
{
preOp=((String)o);
}
}
if(e.target==equalButton)
{
doOperator();
}
return true;
}
public void doOperator()
{
double dFore,dBack;
Double d;
if(preOp.equals(""))
{
backText=foreText;
foreText="";
answerText.setText(backText);
}
else
{
dFore=(new Double(foreText)).doubleValue();
dBack=(new Double(backText)).doubleValue();
foreText="";
backText=answerText.getText();
if(preOp.equals("+"))
{
d=new Double((dBack+dFore));
answerText.setText(d.toString());
backText=d.toString();
}
if(preOp.equals("-"))
{
d=new Double((dBack-dFore));
answerText.setText(d.toString());
backText=d.toString();
}
if(preOp.equals("*"))
{
d=new Double((dBack*dFore));
answerText.setText(d.toString());
backText=d.toString();
}
if(preOp.equals("/"))
{
if(dFore==0)
{
answerText.setText("除数不能为0");
return;
}
d=new Double((dBack/dFore));
answerText.setText(d.toString());
backText=d.toString();
}
}
preOp=currentOp;
}
public void doForeText(String s)
{
foreText +=s;
answerText.setText(foreText);
}
public void doBackText(String s)
{
backText=foreText;
foreText="";
answerText.setText(foreText);
}
public void doClear()
{
currentOp="";
preOp="";
foreText="";
backText="";
isFloat=false;
answerText.setText("");
}
}
package jisuanqi_new;
import java.awt.*;
import java.awt.event.*;
public class JiSuanQi_new implements ActionListener
{
Panel p1;//声明面板p1
TextField t1;//声明文本行t1
String[] label = {"7","8","9","/","4","5","6","*","1","2","3","-","0",".","=","+"};//声明标签数组label1存放按钮上的标签
Button[] b;//声明按钮数组存放16个按钮
private int i;//声明i以备后用
private String op1 = "0";//运算数备用
private String operator = "+";//运算符备用
private boolean append = false;//备用
public JiSuanQi_new()//构造方法
{
t1=new TextField();//初始化文本行t1
b = new Button[label.length];//初始化按钮数组b
p1=new Panel();//初始化面板p1
p1.setLayout(new GridLayout(4,4,4,4));//使面板选择网格布局管理器以备储存16个按钮（4行4列）
for(int i=0;ib.length;i++)//利用for循环把标签放在按钮上，使每个按钮添加事件监听器，在面板p1上添加上16个按钮
{
b[i] = new Button(label[i]);//把标签依次放在16个按钮上
b[i].addActionListener(this);//使每个按钮添加动作事件监听器
p1.add(b[i]); //分别将按钮添加到面板p1上
}
Frame f=new Frame("计算器1.0");//初始化窗口f,起名字计算器1.0
f.setLayout(new BorderLayout());//为窗口选择边界布局管理器
f.add(BorderLayout.NORTH,t1);//把文本行他添加到窗口的北部
f.add(BorderLayout.CENTER,p1);//把面吧p1添加到窗口的中间
f.addWindowListener(new WindowAdapter(){//给窗口f添加窗口事件监听器
public void windowClosing(WindowEvent eve){//运行窗口关闭方法
System.exit(0);//退出程序
}
});
f.setSize(250, 250);//设置窗口大小
f.setLocation(200,200);
f.setVisible(true);//显示窗口
}
public static void main(String args[])
{
new JiSuanQi_new(); //调用构造方法
}
public void actionPerformed(ActionEvent ae)
{//按钮被操作发生
String comm = ae.getActionCommand();//返回与此动作相关的命令字符串，即：使用者第一次点击的按钮是什么。
if("0123456789".indexOf(comm)!=-1)//如果相关命令字符串为0~9之间的数字则执行
{
if(append){
String temp = t1.getText();//新数字
t1.setText(temp+comm);
}else{ //因为此时append为false执行这个
t1.setText(comm); //将文本行t1设置为相关命令字符串（你按中的按钮代码）
append = true;//此时append=true若继续按按钮若继续按数字的话1.第一次的按话不会改变2.非第一次按得话会覆盖之前按得数字（即缺点：只能进行单个数字的计算）
}
}
else if(("+-*/".indexOf(comm)!=-1))//如果相关命令字符串为+-*/之间的数字则执行
{
//保存
//t1.setText(comm);
op1 = t1.getText();//把第一个数赋值给op1
operator = comm;//把命令字符串赋值给operator
append = false;//此时append为false即若继续按按钮若按数字的话将重复上面的动作，按符号的话将覆盖之前的符号
}
else if("=".equals(comm))//如果按的是=号，则按条件进行下面的运算
{
String op2 = t1.getText();//op2第二个数
double d1 = Double.parseDouble(op1);
double d2 = Double.parseDouble(op2);
if(operator.equals("+")){
d1 = d1 + d2 ;
}else if(operator.equals("-")){
d1 = d1 - d2;
}else if(operator.equals("*")){
d1 = d1 * d2;
}else {
d1 = d1 / d2;
}
t1.setText(d1+"");//显示计算结果
append = false;
}
else if(".".equals(comm))//若是.号继续按
{
String temp = t1.getText();
if(temp.indexOf(".")==-1){
t1.setText(temp+".");
append = true;
}
}
}
}
一个简单的计算器功能, 代码不是我写的，其实网上有很多这种例子，我只是整理了一下
package com.zhidao20161213;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
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("计算器");
// 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();
}
}
package importantpg;
import java.awt.*;
import java.awt.event.*;
public class jisuanqi
{
TextArea tf=new TextArea(3,50 );
Button lb=new Button("clear");
Panel p1=new Panel();
Panel p2=new Panel();
public jisuanqi()
{ Frame f=new Frame("计算器");
Panel p=new Panel();
f.setBackground(Color.white);
f.setSize(500, 1500);
f.setVisible(true);
f.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e) {System.exit(1);}
});
Button[] b=new Button[18]; b[10]=new Button("-"); b[15]=new Button("(");
b[11]=new Button("+"); b[12]=new Button("*"); b[16]=new Button(")");
b[13]=new Button("/"); b[14]=new Button("="); b[17]=new Button("退格");
for(int i=0;i=9;++i)
{
b[i]=new Button(""+i);
}
p.setLayout(new GridLayout(6,3));
avent aa=new avent();
lb.addActionListener(aa);
for(int i=0;i18;++i)
{
p.add(b[i]);b[i].addActionListener(aa);
}
p1.setLayout(new BorderLayout());
p1.add(lb,"North");p1.add(tf,"South");f.add(p1, "South");
f.add(p,"Center"); f.pack();
} //构造方法
public static void main(String args[])
{
new jisuanqi();
}
class avent implements ActionListener //事件体
{
public void actionPerformed(ActionEvent e)
{
String s=null; String in="";
s=e.getActionCommand();
if (s!="="s!=nulls!="clear"s!="退格")
{
tf.append(s);
in+=s; s=null;
}
else if(s=="clear")
{
tf.replaceRange("",0,1000);
}else if(s=="=")
{
tf.append("="+jisuan(tf.getText()));
}
else if(s=="退格") {}
}///////////////////////////////////////////////事件处理方法
}
///////////////////////////////////////计算过程//////////////
static String jisuan(String s)
{
String hs= "";
char[] ch = new char[s.length()];
int top = -1;
for (int i = 0; i s.length(); i++)
{
char rsc = s.charAt(i);
switch(rsc)
{
case ' ' : break;
case '+' : //操作符
case '-' :
while (top = 0) //栈不为空时
{
char pc = ch[top--]; //pop Operator
if (pc == '(')
{
ch[++top] = pc; //push Operator
break;
}
else {hs = hs + pc;}
}
ch[++top] = rsc; //push Operator
hs += " ";break;
case '*' : //操作符
case '/' :
while (top = 0) //栈不为空时
{
char c = ch[top--]; //pop Operator
if (c == '(')
{
ch[++top] = c; //push Operator
break;
}
else
{
if (c == '+' || c == '-')
{
ch[++top] = c; //push Operator
break;
}
else
{
hs = hs + c;
}
}
}
ch[++top] = rsc; //push Operator
hs += " ";
break;
case '(' : //操作符
ch[++top] = rsc;
hs+= " ";
break;
case ')' : //操作符
while (top = 0) //栈不为空时
{
char c = ch[top--]; //pop Operator
if (c == '(')
{
break;
}
else
{
hs= hs + c;
}
}
hs += " ";
break;
default : //操作数
hs= hs + rsc;
break;
}//switch
}/////////////////////////////for
while (top = 0)
{
hs= hs + ch[top--]; //pop Operator
}
//System.out.println("hs="+hs); //后缀
//////////////////////////////////////////////后缀////////////////////////////////////
//后缀表达式计算
double[] result = new double[hs.length()];
double x, y;
top = - 1;
String st = "";
for (int i = 0; i hs.length(); i++)
{
char c = hs.charAt(i);
if ((c = '0' c = '9') || c == '.')
{
st += c;
}
if ((c == ' ' st != "") || i == hs.length() - 1)
{
result[++top] = Double.parseDouble(st) ; //push Operands
st = "";
}
if (c == '+' || c == '-' || c == '*' || c == '/')
{
if ((st != ""))
{
result[++top] =Double.parseDouble(st) ; //push Operands
st = "";
}
y = result[top--];
x = result[top--];
switch (c)
{
case '+' :
result[++top] = x+y;break;//push 中间结果再次入栈
case '-' :
result[++top] = x-y;break;
case '*' :
result[++top] = x*y;break;
case '/' :
result[++top] = x/y;break;
default :break;
}
}////////////////////if
} ///////////////////////for
return String.valueOf(result[top]); //pop 最终结果
} /////////////////////////jisuan
}
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()==1s1.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()!=0s2.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();
}
}
