java編寫計(jì)算器實(shí)現(xiàn)退格，倒數(shù)，小數(shù)點(diǎn)，正負(fù)號(hào)功能代碼

import java.awt.*;

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import java.awt.event.*;

import javax.swing.*;

class General extends JFrame implements ActionListener

{

String args[]={"退格","總清","清零","/","1","2","3","+","4","5","6","-","7","8","9","*","0","+/-",".","="};

JButton jb[]=new JButton[20];

JPanel p1=new JPanel();

JTextField jtf=new JTextField(15);

double num1,num2,jieguo;

char c,ch;

public General()

{

Container ct=getContentPane();

jtf.addKeyListener(new KA());

jtf.setHorizontalAlignment(JTextField.RIGHT);

ct.add(jtf,"North");

p1.setLayout(new GridLayout(5,4));

for(int i=0;i20;i++)

{

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

jb[i].addActionListener(this);

p1.add(jb[i]);

}

ct.add(p1);

pack();

setVisible(true);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

public static void main(String args[])

{

new General();

}

public void actionPerformed(ActionEvent e)// 監(jiān)聽按鍵

{

String str=e.getActionCommand().trim();

if("0123456789.".indexOf(str)!=-1)

{

if(jtf.getText().equals("0"))jtf.setText(null);

jtf.setText(jtf.getText()+str);

return;

}

if("+-*/".indexOf(str)!=-1)

{

num1=Double.parseDouble(jtf.getText());

c=str.charAt(0);

jtf.setText(null);

return;

}

else if(str.equals("="))

{

num2=Double.parseDouble(jtf.getText());

switch(c)

{

case '+': jieguo=num1+num2; break;

case '-': jieguo=num1-num2; break;

case '*': jieguo=num1*num2; break;

case '/': jieguo=num1/num2; break;

}

jtf.setText(Double.toString(jieguo));

}

else if(str.equals("+/-"))

{

if(jtf.getText().isEmpty()==false)

{

Double lnum=-(Double.parseDouble(jtf.getText()));

jtf.setText(Double.toString(lnum));

}

else

{

jtf.setText("-");

}

}

else if(str.equals("清空"))

{

jtf.setText(null);

}

else if(str.equals("清零"))

{

jtf.setText("0");

}

else if(str.equals("退格"))

{

jtf.setText(jtf.getText().substring(0,jtf.getText().length()-1));

}

}

class KA extends KeyAdapter // 監(jiān)聽鍵盤

{

public void keyPressed(KeyEvent e)

{

char ch=e.getKeyChar();

if("+-*/".indexOf(ch)!=-1)

{

num1=Double.parseDouble(jtf.getText());

c=ch;

}

if(ch=='='|ch==e.VK_ENTER)

{

num2=Double.parseDouble(jtf.getText());

switch(c)

{

case '+': jieguo=num1+num2; break;

case '-': jieguo=num1-num2; break;

case '*': jieguo=num1*num2; break;

case '/': jieguo=num1/num2; break;

}

}

}

public void keyReleased(KeyEvent e)

{

char ch=e.getKeyChar();

if("+-*/".indexOf(ch)!=-1)

{

jtf.setText(null);

}

if(ch=='='|e.getKeyCode()==e.VK_ENTER)

{

jtf.setText(Double.toString(jieguo));

}

}

}

}

java 退格鍵的控制字符是什么？

是的啊，退格就是\b。你可以用e.KeyCode==8試試。bs(backspace)

我這里有一個(gè)ascii碼，你以后可以對(duì)照看

java 寫計(jì)算器的退格鍵怎么寫，如“123456”按下退格變“12345”

String str = "12345";

str = str.substring(0, str.length()-1);

int a = Integer.parseInt(str);

為什么java中退格符\b不起作用?

可能是因?yàn)閑clipse的console吧。。可能顯示模式是Unicode，然后\b就變成了個(gè)框框。你可以試一下直接在cmd（命令提示符）里面用java命令行跑

有沒有完整的計(jì)算器Java代碼，不要有錯(cuò)誤的，急求

package?jisuanqi;

import?java.awt.BorderLayout;

import?java.awt.Color;

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;

public?class?Calculator?extends?JFrame?implements?ActionListener{?????//建一個(gè)Calculator類繼承JFrame實(shí)現(xiàn)ActionListener

public?static?void?main?(String?args[]){

Calculator?calculator=new?Calculator();?????//創(chuàng)建對(duì)象calculator

calculator.setVisible(true);???????????????//窗口可見

calculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);??//關(guān)閉圖標(biāo)后結(jié)束程序

}

String?keys?[]={"7","8","9","/","4","5","6","*","1","2","3","-","0",".","=","+"};//表示計(jì)算器的鍵的名字

String?command?[]={"backspace","C"};//功能鍵

JButton?KEYS?[]=new?JButton[keys.length];//創(chuàng)建鍵對(duì)象

JButton?COMMAND[]=new?JButton[command.length];//功能鍵對(duì)象

static?JTextField?resultSet=new?JTextField();//建一個(gè)文本框

double?resultNum;????????//結(jié)果

String?operator="";//運(yùn)算符??---------------------------

public?Calculator()?{//????構(gòu)造函數(shù)

super();??????

init();//初始化計(jì)算器

this.setBackground(Color.WHITE);//this代表用當(dāng)前構(gòu)造方法創(chuàng)建的對(duì)象

this.setTitle("簡(jiǎn)單計(jì)算器");????//窗口標(biāo)題

this.setLocation(500,?300);???//窗口大小

this.pack(); //使組件大小合適

}

void?init()?{??????//初始化計(jì)算器

resultSet.setHorizontalAlignment(JTextField.RIGHT);?????//設(shè)置文本框內(nèi)容向右對(duì)齊

resultSet.setBackground(Color.WHITE);???????????//設(shè)置文本框背景顏色

JPanel?keysPanel=new?JPanel();//創(chuàng)建一個(gè)面板

keysPanel.setLayout(new?GridLayout(4,5,3,3));?//設(shè)置面板的布局為網(wǎng)格型

for?(int?i=0;ikeys.length;i++)?{??????//把數(shù)字鍵和符號(hào)鍵設(shè)為按鈕

KEYS[i]=new?JButton(keys[i]);

keysPanel.add(KEYS[i]);????????????//把按鈕加到面板中

}

JPanel?comPanel=new?JPanel();???????//創(chuàng)建命令鍵面板

comPanel.setLayout(new?GridLayout(1,2,3,3));//設(shè)置面板布局為網(wǎng)格型?

for(int?i=0;icommand.length;i++)?{????//把命令鍵設(shè)置為按鈕

COMMAND[i]=new?JButton(command[i]);

comPanel.add(COMMAND[i]);??????????//把按鈕放到面板上

}

JPanel?pane=new?JPanel();??????//創(chuàng)建面板

pane.setLayout(new?BorderLayout());??//面板布局為區(qū)域型

pane.add(comPanel,BorderLayout.NORTH);?????//把命令面板加入到大面板上

pane.add(keysPanel,BorderLayout.CENTER); //把數(shù)字鍵面板加到大面板

getContentPane().setLayout(new?BorderLayout());?????//設(shè)置底層容器的布局為區(qū)域型

getContentPane().add(resultSet,BorderLayout.NORTH);???//把文本框放到北面

getContentPane().add(pane,BorderLayout.CENTER);????//把大面板放到中央

for(int?i=0;ikeys.length;i++){

KEYS[i].addActionListener(this);//為按鈕添加監(jiān)聽器

}

for(int?i=0;icommand.length;i++){

COMMAND[i].addActionListener(this);???

}

}

//處理事件 ?

public?void?actionPerformed(ActionEvent?e){??

String?lable=e.getActionCommand();

if(lable.equals("backspace")){??????//如果命令為backspace

backspace();

}

else?if?(lable.equals("C")){?????//如果命令為C

Clear();

}

else?if?(Character.isDigit(lable.charAt(0)))?{???????//---------------

if(resultSet.getText().equals("0")){

resultSet.setText("");

}

resultSet.setText(resultSet.getText()+lable);

}

else?if?(lable.equals(".")){

point();

}

else?if?(lable.equals("=")){

equal();

}

else?{

doOperation();

resultSet.setText("");

operator=lable;

}

}

void?point()?{

String?s=resultSet.getText();

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

resultSet.setText(s+".");

}

}

void?equal()?{

doOperation();

resultSet.setText(""+resultNum);

operator="";

}

void?doOperation()?{

double?m=Double.parseDouble(resultSet.getText());

if(operator.equals("")){

resultNum=m;

}

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

resultNum+=m;

}

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

resultNum-=m;

}

if(operator.equals("*")){

resultNum*=m;

}

if(operator.equals("/")){

resultNum/=m;

}

}

void?Clear()?{?????//清零

resultSet.setText("0");

}

void?backspace()?{????//退格

String?text?=resultSet.getText();

if?(text.length()0){

resultSet.setText(text.substring(0,?text.length()-1));//將文本最后一個(gè)字符刪除

}

else?if?(text.length()==0){

resultSet.setText("0");

}

}

}

Java中轉(zhuǎn)義退格字符的問題

\b?代表?一個(gè)單詞的邊界

這是?JDK1.6?中的?API?說的

\b是正則表達(dá)式規(guī)定的一個(gè)特殊代碼（某些人叫它元字符，metacharacter），代表著單詞的開頭或結(jié)尾，也就是單詞的分界處。雖然通常英文的單詞是由空格，標(biāo)點(diǎn)符號(hào)或者換行來分隔的，但是\b并不匹配這些單詞分隔字符中的任何一個(gè)，它只匹配一個(gè)位置

;nbsp;??如何這篇文章你能看完，相信一定對(duì)你有相當(dāng)大的幫忙

本文標(biāo)題：java退格代碼 Java退格
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