java实现简单计算器功能

童鞋们，是不是有使用计算器的时候，还要进入运行，输入calc，太麻烦了，有时候甚至还忘记单词怎么拼写，呵呵
程序员自己写代码实现，又简单，又方便啊

package com;

import java.awt.BorderLayout;

import java.awt.EventQueue;

import java.awt.Font;

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.JPanel;

import javax.swing.JTextField;

import javax.swing.SwingConstants;

import javax.swing.UIManager;

import javax.swing.border.EmptyBorder;

public class Test  extends JFrame{

/**

*  humphrey

*/

private static final long serialVersionUID = -9075562467166618473L;

private JPanel contentPane;

private JTextField display;

private ActionListener insert = new InsertAction();

private ActionListener command = new CommandAction();

private double result = 0;

private String lastCommand = "=";

private boolean start = true;

/**

* Launch the application.

*/

public static void main(String[] args) {

try {

UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");

} catch (Throwable e) {

e.printStackTrace();

}

EventQueue.invokeLater(new Runnable() {

public void run() {

try {

Test frame = new Test();

frame.setVisible(true);

} catch (Exception e) {

e.printStackTrace();

}

}

});

}

/**

* Create the frame.

*/

public Test() {

setTitle("\u8BA1\u7B97\u5668");

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setLocationByPlatform(true);

contentPane = new JPanel();

contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));

contentPane.setLayout(new BorderLayout(0, 0));

setContentPane(contentPane);

JPanel displayPanel = new JPanel();

contentPane.add(displayPanel, BorderLayout.NORTH);

display = new JTextField();

display.setText("0");

display.setHorizontalAlignment(SwingConstants.RIGHT);

display.setEditable(false);

display.setFont(new Font("微软雅黑", Font.PLAIN, 15));

displayPanel.add(display);

display.setColumns(13);

JPanel buttonPanel = new JPanel();

contentPane.add(buttonPanel, BorderLayout.CENTER);

buttonPanel.setLayout(new GridLayout(4, 4, 5, 5));

JButton number7Button = new JButton("7");

number7Button.addActionListener(insert);

number7Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number7Button);

JButton number8Button = new JButton("8");

number8Button.addActionListener(insert);

number8Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number8Button);

JButton number9Button = new JButton("9");

number9Button.addActionListener(insert);

number9Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number9Button);

JButton divideButton = new JButton("/");

divideButton.addActionListener(command);

divideButton.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(divideButton);

JButton number4Button = new JButton("4");

number4Button.addActionListener(insert);

number4Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number4Button);

JButton number5Button = new JButton("5");

number5Button.addActionListener(insert);

number5Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number5Button);

JButton number6Button = new JButton("6");

number6Button.addActionListener(insert);

number6Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number6Button);

JButton multiplyButton = new JButton("*");

multiplyButton.addActionListener(command);

multiplyButton.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(multiplyButton);

JButton number3Button = new JButton("1");

number3Button.addActionListener(insert);

number3Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number3Button);

JButton number2Button = new JButton("2");

number2Button.addActionListener(insert);

number2Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number2Button);

JButton number1Button = new JButton("3");

number1Button.addActionListener(insert);

number1Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number1Button);

JButton subtractButton = new JButton("-");

subtractButton.addActionListener(command);

subtractButton.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(subtractButton);

JButton number0Button = new JButton("0");

number0Button.addActionListener(insert);

number0Button.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(number0Button);

JButton dotButton = new JButton(".");

dotButton.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(dotButton);

JButton equalButton = new JButton("=");

equalButton.addActionListener(command);

equalButton.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(equalButton);

JButton addButton = new JButton("+");

addButton.addActionListener(command);

addButton.setFont(new Font("微软雅黑", Font.PLAIN, 15));

buttonPanel.add(addButton);

pack();

}

private class InsertAction implements ActionListener {

public void actionPerformed(ActionEvent e) {

String input = e.getActionCommand();

String text = display.getText();

if (start) {

display.setText("");

start = false;

}

if (text.startsWith(".")) {

display.setText("0" + display.getText() + input);

} else if (text.startsWith("-0.") || text.startsWith("0.")) {

display.setText(display.getText() + input);

} else if (text.startsWith("-0")) {

display.setText("-" + input);

} else if (text.startsWith("0")) {

display.setText(input);

} else {

display.setText(display.getText() + input);

}

}

}

private class CommandAction implements ActionListener {

public void actionPerformed(ActionEvent e) {

String command = e.getActionCommand();

if (start) {

if (command.equals("-")) {

display.setText(command);

start = false;

} else {

lastCommand = command;

}

} else {

calculate(Double.parseDouble(display.getText()));

lastCommand = command;

start = true;

}

}

}

public void calculate(double x) {

char operator = lastCommand.charAt(0);

switch (operator) {

case '+':

result += x;

break;

case '-':

result -= x;

break;

case '*':

result *= x;

break;

case '/':

result /= x;

break;

case '=':

result = x;

break;

}

display.setText("" + result);

}

}