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package chp13;

import java.util.*;

import java.util.Stack;

import java.awt.BorderLayout;

import java.awt.GridBagConstraints;

import java.awt.GridBagLayout;

import java.awt.RenderingHints.Key;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.KeyEvent;

import java.awt.event.KeyListener;

import java.beans.Expression;

import java.util.Scanner;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import javax.swing.*;

public class Exercise13_05 extends JFrame implements KeyListener, ActionListener {

JTextField text;

String display;

boolean flag=false;

void init()

{

setTitle("计算器示例");

text=new JTextField("0.0");

text.setEditable(false);

text.setHorizontalAlignment(JTextField.RIGHT);//居右显示

add(text, BorderLayout.NORTH);

text.addKeyListener(this);

JPanel p = new JPanel();//设置一个JPanel容器对象

GridBagLayout layout = new GridBagLayout();

p.setLayout(layout);

String[] name = {"C","←","*","÷","7","8","9","-","4","5","6","+","1","2","3","=","0","."};

JButton [] button=new JButton[name.length];

for (int i = 0; i < name.length; ++i)

{

button[i]=new JButton(name[i]);

button[i].setActionCommand(name[i]);

button[i].addActionListener(this);

//button[i].addKeyListener(this);

}

GridBagConstraints s= new GridBagConstraints();//定义一个GridBagConstraints，

s.fill = GridBagConstraints.BOTH;//使组件充满显示区域

for(int i=1;i<16;i++)

{

if(i%4!=0)

s.gridwidth=1;//设置组件水平所占用的网格数，如果为0，组件是该行的最后一个

else

s.gridwidth=0;

s.weightx = 1;//设置组件水平的拉伸幅度，为0不拉伸，不为0就随着窗口增大进行拉伸

s.weighty=1;//设置组件垂直的拉伸幅度，为0不拉伸，不为0就随着窗口增大进行拉伸

p.add(button[i-1],s);//将生成的按钮按照GridBagConstraints设置位置进行添加

}

s.gridwidth=0;

s.gridheight=2;

s.weightx = 1;

s.weighty=1;

p.add(button[15],s);//将“=”按钮设置为占用两行一列

s.gridx=0;

s.gridy=4;

s.gridheight=1;

s.gridwidth=2;

s.weightx = 1;

s.weighty=1;

p.add(button[16],s);//将“0”按钮设置在第4行，第0列显示，并占用两列一行，添加入面板

s.gridx=2;

s.gridy=4;

s.gridwidth=1;

s.gridheight=1;

s.weightx = 0;

s.weighty=0;

p.add(button[17],s);//将“.”按钮设置在第4行，第2列显示，添加入面板

add(p);//将JPanel容器加入到窗口中，默认为中间位置

setSize(250,250);//设置窗口大小为250*250

setVisible(true);

setDefaultCloseOperation(EXIT_ON_CLOSE);

}

public void actionPerformed(ActionEvent e) {

if (flag==true){

text.setText("0.0");

flag=false;

}

String content=text.getText();

if(!content.equals("0.0")){//计算器为非初始状态

if(e.getActionCommand().equals("C")){//如果计算器清零

text.setText("0.0");

}

else

{

if((e.getActionCommand().equals("←"))){//删除字符串最后一个字符

if(content.length()>1)

text.setText(content.substring(0, content.length()-1));

else

text.setText("0.0");

}

else

{//输入任意字符

Pattern pattern=Pattern.compile("\d$");

Matcher matcher=pattern.matcher(content);

if(matcher.find()){//如果字符串最后是数字，可以输入任何信息

//text.setText(content+e.getActionCommand());

if(e.getActionCommand().equals("=")){

String name=text.getText();

calculate expression = new calculate(name+"#");

expression.solve();

double result = expression.operate();

text.setText(String.valueOf(result));

flag=true;

}

else{

text.setText(content+e.getActionCommand());

}

}

else{//否则只能输入数字

java语言基础篇课后答案在哪找 matcher=pattern.matcher(e.getActionCommand());

if(matcher.find()){//如果是数字，可以输入

text.setText(content+e.getActionCommand());

}

}

}

}

}

else{

Pattern pattern=Pattern.compile("\d$");

Matcher matcher=pattern.matcher(e.getActionCommand());

if(matcher.find()){

text.setText(e.getActionCommand());

}

}

}

public void keyTyped(KeyEvent e) {}

public void keyPressed(KeyEvent e) {}

public void keyReleased(KeyEvent e) {}

public static void main(String s[]){

new Exercise13_05().init();

}

}

class calculate {

Stack<Character> stack = new Stack<Character>();

char a[]=new char[100];

char b[]=new char[100];// 后缀表达式

public calculate(String in){

this.a = in.toCharArray();

solve();

}

public int priority(char operator){

switch (operator) {//运算符优先级

case '+':

return 1;

case '-':

return 1;

case '*':

return 2;

case '÷':

return 2;

case '(':

return 0;

default:

return -1;

}

}

public void solve() {//字符串解析

stack.push('#');

int la = a.length;

int j = 0;

boolean flag = true;//有数字

for(int i = 0;i < la;i++){

if(a[i] >= '0' && a[i] <= '9' || a[i] == '.'){

b[j++] = a[i];

flag = true;

}

else if(a[i] == '('){

stack.push(a[i]);

}

else if(a[i] == ')'){

if(flag == true){

b[j++] = ' ';

flag = false;

}

while(stack.peek() !='('){

b[j++]=stack.peek();

stack.pop();

}

stack.pop();

}

else{

if(flag == true){

b[j++] = ' ';

flag = false;

}

while( priority(stack.peek()) >= priority(a[i]) && stack.peek() != '#'){

b[j++] = stack.peek();

stack.pop();

}

stack.push(a[i]);

}

}

while(stack.peek() != '#'){

b[j++] = stack.peek();

stack.pop();

}

b[j] = '

';

}

public double operate() {

double res = 0;

double sum = 0;

int position = 0;

boolean xiaoshu = false;

double dianwei = 0.1;

Stack<Double> stack_operate = new Stack<Double>();

while(b[position] != '

'){

if(b[position] >= '0' && b[position] <='9'){

if(xiaoshu == false) res = res*10+b[position]-'0';

else{

res = res+dianwei*(b[position]-'0');

dianwei = dianwei*0.1;

}

}

else if(b[position] == '.'){

xiaoshu = true;

}

else if(b[position] == ' '){

xiaoshu = false;

dianwei = 0.1;

if(res != 0){

stack_operate.push(res);

res = 0;

}

}

else{

double x1 = stack_operate.peek();

stack_operate.pop();

double x2 = stack_operate.peek();

stack_operate.pop();

if(b[position] == '+') sum = x1+x2;

else if(b[position] == '-') sum = x2-x1;

else if(b[position] == '*') sum = x2*x1;

else if (b[position] == '÷') sum = x2/x1;

stack_operate.push(sum);

res = 0;

}

position++;

}

return sum;

}