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用java编写一个简单计算器
/////calculator.java代码
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.event.*;
public class calculator extends JApplet{
Container contentPane;
JButton btn0 = new JButton();
JButton btn1 = new JButton();
JButton btn2 = new JButton();
JButton btn3 = new JButton();
JButton btn4 = new JButton();
JButton btn5 = new JButton();
JButton btn6 = new JButton();
JButton btn7 = new JButton();
JButton btn8 = new JButton();
JButton btn9 = new JButton();
//特殊按钮
JButton btnClear = new JButton(); //清除
JButton btnEqual = new JButton(); //等于
JButton btnPlus = new JButton(); //+操作符
JButton btnMinus = new JButton(); //-操作符
JButton btnMultiply = new JButton(); //*操作符
JButton btnDivide = new JButton(); //除操作符
JTextField texResult = new JTextField();
boolean flag=false;
String operand1;
String operand2;
double result;
String action;
public void init(){
contentPane = getContentPane();
contentPane.setLayout(null);
setSize(new Dimension(250, 250));
btn0.setBounds(new Rectangle(50, 230, 45, 45));
btn0.setFont(new java.awt.Font("Tahoma", Font.PLAIN, 14));
btn0.setText("0");
btn0.addActionListener(new btn0(this));
//清除操作符
btnClear.setBounds(new Rectangle(100,230,45,45));
btnClear.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btnClear.setText("C");
btnClear.addActionListener(new btnClear(this));
//=操作符
btnEqual.setBounds(new Rectangle(150,230,45,45));
btnEqual.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btnEqual.setText("=");
btnEqual.addActionListener(new btnEqual(this));
//+操作符
btnPlus.setBounds(new Rectangle(200,230,45,45));
btnPlus.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btnPlus.setText("+");
btnPlus.addActionListener(new btnPlus(this));
btn1.setBounds(new Rectangle(50,180,45,45));
btn1.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn1.setText("1");
btn1.addActionListener(new btn1(this));
btn2.setBounds(new Rectangle(100,180,45,45));
btn2.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn2.setText("2");
btn2.addActionListener(new btn2(this));
btn3.setBounds(new Rectangle(150,180,45,45));
btn3.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn3.setText("3");
btn3.addActionListener(new btn3(this));
//-操作符
btnMinus.setBounds(new Rectangle(200,180,45,45));
btnMinus.setFont(new java.awt.Font("Tahoma",Font.PLAIN,16));
btnMinus.setText("-");
btnMinus.addActionListener(new btnMinus(this));
btn4.setBounds(new Rectangle(50,130,45,45));
btn4.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn4.setText("4");
btn4.addActionListener(new btn4(this));
btn5.setBounds(new Rectangle(100,130,45,45));
btn5.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn5.setText("5");
btn5.addActionListener(new btn5(this));
btn6.setBounds(new Rectangle(150,130,45,45));
btn6.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn6.setText("6");
btn6.addActionListener(new btn6(this));
//*操作符
btnMultiply.setBounds(new Rectangle(200,130,45,45));
btnMultiply.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btnMultiply.setText("*");
btnMultiply.addActionListener(new btnMultiply(this));
btn7.setBounds(new Rectangle(50,80,45,45));
btn7.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn7.setText("7");
btn7.addActionListener(new btn7(this));
btn8.setBounds(new Rectangle(100,80,45,45));
btn8.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn8.setText("8");
btn8.addActionListener(new btn8(this));
btn9.setBounds(new Rectangle(150,80,45,45));
btn9.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btn9.setText("9");
btn9.addActionListener(new btn9(this));
//除操作符
btnDivide.setBounds(new Rectangle(200,80,45,45));
btnDivide.setFont(new java.awt.Font("Tahoma",Font.PLAIN,14));
btnDivide.setText("/");
btnDivide.addActionListener(new btnDivide(this));
texResult.setText("");
texResult.setBounds(new Rectangle(40, 35, 215, 35));
texResult.setFont(new java.awt.Font("Tahoma", Font.PLAIN, 14));
texResult.setHorizontalAlignment(JTextField.RIGHT);
contentPane.add(btn0);
contentPane.add(btn1);
contentPane.add(btn2);
contentPane.add(btn3);
contentPane.add(btn4);
contentPane.add(btn5);
contentPane.add(btn6);
contentPane.add(btn7);
contentPane.add(btn8);
contentPane.add(btn9);
contentPane.add(btnClear);
contentPane.add(btnEqual);
contentPane.add(btnPlus);
contentPane.add(btnMinus);
contentPane.add(btnMultiply);
contentPane.add(btnDivide);
contentPane.add(texResult);
}
//0的事件监听器
public void btn0_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn0.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn0.getActionCommand());
}
}
class btn0 implements ActionListener{
private calculator adaptee;
btn0(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn0_actionPerformed(e);
}
}
//1的事件监听器
public void btn1_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn1.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn1.getActionCommand());
}
}
class btn1 implements ActionListener{
private calculator adaptee;
btn1(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn1_actionPerformed(e);
}
}
//2的事件监听器
public void btn2_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn2.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn2.getActionCommand());
}
}
class btn2 implements ActionListener{
private calculator adaptee;
btn2(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn2_actionPerformed(e);
}
}
//3的事件监听器
public void btn3_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn3.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn3.getActionCommand());
}
}
class btn3 implements ActionListener{
private calculator adaptee;
btn3(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn3_actionPerformed(e);
}
}
//4的事件监听器
public void btn4_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn4.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn4.getActionCommand());
}
}
class btn4 implements ActionListener{
private calculator adaptee;
btn4(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn4_actionPerformed(e);
}
}
//5的事件监听器
public void btn5_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn5.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn5.getActionCommand());
}
}
class btn5 implements ActionListener{
private calculator adaptee;
btn5(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn5_actionPerformed(e);
}
}
//6的事件监听器
public void btn6_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn6.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn6.getActionCommand());
}
}
class btn6 implements ActionListener{
private calculator adaptee;
btn6(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn6_actionPerformed(e);
}
}
//7的事件监听器
public void btn7_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn7.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn7.getActionCommand());
}
}
class btn7 implements ActionListener{
private calculator adaptee;
btn7(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn7_actionPerformed(e);
}
}
//8的事件监听器
public void btn8_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn8.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn8.getActionCommand());
}
}
class btn8 implements ActionListener{
private calculator adaptee;
btn8(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn8_actionPerformed(e);
}
}
//9的事件监听器
public void btn9_actionPerformed(ActionEvent e){
if(flag){
texResult.setText(btn9.getActionCommand());
flag = false;
}
else{
texResult.setText(texResult.getText()+btn9.getActionCommand());
}
}
class btn9 implements ActionListener{
private calculator adaptee;
btn9(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btn9_actionPerformed(e);
}
}
//清除操作
public void btnClear_actionPerformed(ActionEvent e){
texResult.setText("");
}
class btnClear implements ActionListener{
private calculator adaptee;
btnClear(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btnClear_actionPerformed(e);
}
}
//+操作事件监听器
public void btnPlus_actionPerformed(ActionEvent e){
operand1 = texResult.getText();
action = "plus";
flag = true;
}
class btnPlus implements ActionListener{
private calculator adaptee;
btnPlus(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btnPlus_actionPerformed(e);
}
}
//-操作事件监听器
public void btnMinus_actionPerformed(ActionEvent e){
operand1 = texResult.getText();
action = "minus";
flag = true;
}
class btnMinus implements ActionListener{
private calculator adaptee;
btnMinus(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btnMinus_actionPerformed(e);
}
}
//*操作事件监听器
public void btnMultiply_actionPerformed(ActionEvent e){
operand1 = texResult.getText();
action = "multiply";
flag = true;
}
class btnMultiply implements ActionListener{
private calculator adaptee;
btnMultiply(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btnMultiply_actionPerformed(e);
}
}
//除操作事件监听器
public void btnDivide_actionPerformed(ActionEvent e){
operand1 = texResult.getText();
action = "divide";
flag = true;
}
class btnDivide implements ActionListener{
private calculator adaptee;
btnDivide(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btnDivide_actionPerformed(e);
}
}
//=操作事件监听器
public void btnEqual_actionPerformed(ActionEvent e){
double digit1;
double digit2;
operand2 = texResult.getText();
if(!flag){
if(action.equals("plus")){
digit1 = Double.parseDouble(operand1);
digit2 = Double.parseDouble(operand2);
result = digit1 + digit2;
texResult.setText("" + result);
flag = true;
}
else if(action.equals("minus")){
digit1 = Double.parseDouble(operand1);
digit2 = Double.parseDouble(operand2);
result = digit1 - digit2;
texResult.setText(""+result);
flag = true;
}
else if(action.equals("multiply")){
digit1 = Double.parseDouble(operand1);
digit2 = Double.parseDouble(operand2);
result = digit1 * digit2;
texResult.setText(""+result);
flag = true;
}
else if(action.equals("divide")){
digit1 = Double.parseDouble(operand1);
digit2 = Double.parseDouble(operand2);
result = digit1 / digit2;
texResult.setText(""+result);
flag = true;
}
}
}
class btnEqual implements ActionListener{
private calculator adaptee;
btnEqual(calculator adaptee){
this.adaptee=adaptee;
}
public void actionPerformed(ActionEvent e){
adaptee.btnEqual_actionPerformed(e);
}
}
}
////calculator.html文件代码
<html>
<head><title>计算器</title></head>
<center>
<applet code=calculator.class width=300 height=300>
</applet>
</center>
</html>
以上只要有java运行环境JDK，将calculator.java文件编译，然后建一文本文件，直接运行calculator.html就可以看到效果，不过不可以连乘、除、加、减不足之处多多指点。
