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package com.citi.Util;

import java.awt.BorderLayout;

import java.awt.GridLayout;

import java.awt.Toolkit;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.*;

/**

* @author yc80549

*

*/

public class Calculator extends JFrame implements ActionListener {

/**

*

*

*/

private static final long serialVersionUID = 1L;

private JTextField expression = new JTextField();

private JPanel buttonContainer = new JPanel();

private JPanel operators = new JPanel();

private JButton b1 = new JButton("1");

private JButton b2 = new JButton("2");

private JButton b3 = new JButton("3");

private JButton b4 = new JButton("4");

private JButton b5 = new JButton("5");

private JButton b6 = new JButton("6");

private JButton b7 = new JButton("7");

private JButton b8 = new JButton("8");

private JButton b9 = new JButton("9");

private JButton b0 = new JButton("0");

private JButton bpoint = new JButton(".");

private JButton bracket1 = new JButton("(");

private JButton bracket2 = new JButton(")");

private JButton plus = new JButton("+");

private JButton minus = new JButton("-");

private JButton multiply = new JButton("*");

private JButton divide = new JButton("/");

private JButton getResult = new JButton("=");

private JButton backSpace = new JButton("Backspace");

private JButton clear = new JButton("C");

private JButton OFF = new JButton("OFF");

private StringCalculate2 cacu = new StringCalculate2();

public Calculator() {

super();

setVisible(true);

this.setLayout(new BorderLayout());

this.setSize(400, 220);

Toolkit tk = Toolkit.getDefaultToolkit();

int width = (int) tk.getScreenSize().getWidth();

int height = (int) tk.getScreenSize().getHeight();

this.setLocation((int) ((width - getSize().getWidth()) / 2),

(int) ((height - getSize().getHeight()) / 2));

this.locate();

this.addAllListener();

}

public void locate() {

buttonContainer.setLayout(new GridLayout(4, 4));

buttonContainer.add(b1);

buttonContainer.add(b2);

buttonContainer.add(b3);

buttonContainer.add(plus);

buttonContainer.add(b4);

buttonContainer.add(b5);

buttonContainer.add(b6);

buttonContainer.add(minus);

buttonContainer.add(b7);

buttonContainer.add(b8);

buttonContainer.add(b9);

buttonContainer.add(multiply);

buttonContainer.add(b0);

buttonContainer.add(bpoint);

buttonContainer.add(getResult);

buttonContainer.add(divide);

operators.add(bracket1);

operators.add(bracket2);

operators.add(backSpace);

operators.add(clear);

operators.add(OFF);

this.add(expression, BorderLayout.NORTH);

this.add(buttonContainer, BorderLayout.CENTER);

this.add(operators, BorderLayout.SOUTH);

}

public void addAllListener() {

b1.addActionListener(this);

b2.addActionListener(this);

b3.addActionListener(this);

b4.addActionListener(this);

b5.addActionListener(this);

b6.addActionListener(this);

b7.addActionListener(this);

b8.addActionListener(this);

b9.addActionListener(this);

b0.addActionListener(this);

plus.addActionListener(this);

multiply.addActionListener(this);

divide.addActionListener(this);

minus.addActionListener(this);

bpoint.addActionListener(this);

bracket1.addActionListener(this);

bracket2.addActionListener(this);

getResult.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

try {

double result = cacu.parse(expression.getText());

expression.setText("" + result);

} catch (Exception e1) {

System.err

.println("invaild expression or RuntimeException");

}

}

});

clear.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

expression.setText("");

}

});

OFF.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

System.exit(1);

}

});

backSpace.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

expression.setText(expression.getText().substring(0,

expression.getText().length() - 1));

}

});

}

public void actionPerformed(ActionEvent e) {

JButton source = (JButton) e.getSource();

expression.setText(expression.getText() + source.getText());

}

public static void main(String[] args) {

Calculator cal = new Calculator();

cal.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

}

package com.citi.Util;

import java.util.Stack;

import javax.swing.JOptionPane;

public class StringCalculate2 {

private Stack numbers = new Stack();

private Stack chs = new Stack();

private boolean compare(char str) {

32313133353236313431303231363533e59b9ee7ad9431333335313831if (chs.empty()) {

return true;

}

char last = (char) chs.lastElement();

switch (str) {

case '*': {

if (last == '+' || last == '-')

return true;

else

return false;

}

case '/': {

if (last == '+' || last == '-')

return true;

else

return false;

}

case '+':

return false;

case '-':

return false;

}

return true;

}

public Double caculate(String str) {

StringBuffer sb = new StringBuffer(str);

StringBuffer num = new StringBuffer();

String tem = null;

char next;

while (sb.length() > 0) {

tem = sb.substring(0, 1);

sb.delete(0, 1);

if (isNum(tem.trim())) {

num.append(tem);

} else {

if (num.length() > 0 && !"".equals(num.toString().trim())) {

Double d = new Double(num.toString().trim());

numbers.push(d);

num.delete(0, num.length());

}

if (!chs.isEmpty()) {

while (!compare(tem.charAt(0))) {

caculate();

}

}

if (numbers.isEmpty()) {

num.append(tem);

} else {

chs.push(new Character(tem.charAt(0)));

}

next = sb.charAt(0);

if (next == '-') {

num.append(next);

sb.delete(0, 1);

}

}

}

Double d = new Double(num.toString().trim());

numbers.push(d);

while (!chs.isEmpty()) {

caculate();

}

return numbers.pop();

}

public void caculate() {

Double b = numbers.pop();

Double a = null;

a = numbers.pop();

char ope = chs.pop();

Double result = null;

switch (ope) {

case '+':

result = a + b;

numbers.push(result);

break;

case '-':

result = a - b;

numbers.push(result);

break;

case '*':

result = a * b;

numbers.push(result);

break;

case '/':

result = a / b;

numbers.push(result);

break;

}

}

private boolean isNum(String num) {

return num.matches("[0-9.]");

}

public Double parse(String str) {

int start = 0;

StringBuffer sts = new StringBuffer(str);

int end = -1;

while ((end = sts.indexOf(")")) > 0) {

String s = sts.substring(start, end + 1);

int first = s.lastIndexOf("(");

Double value = caculate(sts.substring(first + 1, end));

sts.replace(first, end + 1, value.toString());

}

return caculate(sts.toString());

}

public static void main(String[] args) {

String exp = JOptionPane

.showInputDialog("please input expression you want to caculate!");

if (exp.trim().equals("")) {

System.out.println("you have input nothing");

return;

}

StringCalculate2 sc = new StringCalculate2();

JOptionPane.showMessageDialog(null, "the result is: " + sc.parse(exp));

}

}

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