用Java写的计算器

package com.wenbo.myprogrem.day15;

import java.awt.*;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.*;

public class Caculator implements ActionListener{

String result="0";

String oper="+";//运算符

Double res;

StringBuilder sb=new StringBuilder();

JTextField jtf = new JTextField(10);

private boolean append=false;

public Caculator(){

JFrame jf = new JFrame("简易计算器");

JPanel jp = new JPanel();

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

String[] lab = {"Backs","CE","E","+","7","8","9",

"-","4","5","6","*","1","2","3",

"/","0","+/-",".","="};

for (int i=0; i <20; i++) {

JButton jb = new JButton(lab[i]);

jb.addActionListener(this);//给每个按钮注册监听器

jp.add(jb);

}

jf.setResizable(false);

jf.add(jp);

jtf.addActionListener(this);

jf.add(jtf,BorderLayout.NORTH);

jf.setSize(320,240);//像素

jf.setLocation(300,200);//设置出现位置

jf.setVisible(true);

jf.setDefaultCloseOperation(//设置X

JFrame.EXIT_ON_CLOSE);

}

public void actionPerformed(ActionEvent e) {

String comm=e.getActionCommand();//获得按钮上的文字

System.out.println(comm);

if("0123456789".indexOf(comm)!=-1){

if(append){//追加，刚开始是false按完数字键之后是变成true

String temp=jtf.getText();

jtf.setText(temp+comm);

}else{//替换

jtf.setText(comm);

append=true;

}

}else if("+-/*".indexOf(comm)!=-1){//当按到运算符时的处理

result=jtf.getText();//把输入框的内容存起来

oper=comm;

append=false;//不显示运算符，等待下次输入数字

}else if("=".equals(comm)){//计算过程

String s2=jtf.getText();

double d1=Double.parseDouble(result);

double d2=Double.parseDouble(s2);

if("+".equals(oper)){

d1=d1+d2;

}else if("*".equals(oper)){

d1=d1*d2;

}else if("/".equals(oper)){

d1=d1/d2;

}

result=d1+"";//将计算后的结果显示在输入框中

jtf.setText(result);

append=false;

}else if(".".equals(comm)){

String temp=jtf.getText();

if(temp.indexOf(".")==-1){

jtf.setText(temp+".");

append=true;

}

}else if("+/-".equals(comm)){

String temp=jtf.getText();

if(temp.startsWith("-")){//如果是以-开头的数

jtf.setText(temp.substring(1));//用substring截取从第二个字符开始，前面的-不要

}else{

jtf.setText("-"+temp);

}

append=true;

}else if("CE".equals(comm)||"C".equals(comm)){

jtf.setText("0");

}else if("Backs".equals(comm)){

}

}

public static void main(String[] args) {

new Caculator();

}

}