JAVA 编写计算器 要代码最简单的

学java的时候自己编的，很简单，能够连续输入计算式后进行计算

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import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.FlowLayout;

import java.awt.Font;

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.text.NumberFormat;

import java.util.ArrayList;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JTextField;

/**简易计算器，能够进行简单的计算

*

* @see 2008.12.9

*/

public class CalculatorA

implements ActionListener{

private JFrame frame;

private JTextField field;

private JButton[] allButtons;

private JButton clearButton;

// private JButton backButton;

String result="";//保存结果

StringBuilder sb = new StringBuilder();//保存要进行的计算式

int x = 0; //用来判断上一次的事件类型

String str = "123+456-789*0.=/";

ArrayListString arrayList = new ArrayListString();//保存计算式，通过方法进行运算

public CalculatorA(){

frame = new JFrame("我的计算器v1.1");

frame.setLocation(300,300);

field = new JTextField(25);

allButtons = new JButton[16];

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

allButtons[i]= new JButton(str.substring(i,i+1));

}

clearButton = new JButton("CLEAR");

// backButton = new JButton("——");

init();

setFondAndColor();

addEventHander();

}

public void init(){

frame.setLayout(new BorderLayout());

JPanel northPanel = new JPanel();

JPanel centerPanel = new JPanel();

JPanel southPanel = new JPanel();

northPanel.setLayout(new FlowLayout());

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

southPanel.setLayout(new FlowLayout());

northPanel.add(field);

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

centerPanel.add(allButtons[i]);

}

southPanel.add(clearButton);

//southPanel.add(backButton);

frame.add(northPanel,BorderLayout.NORTH);

frame.add(centerPanel,BorderLayout.CENTER);

frame.add(southPanel,BorderLayout.SOUTH);

}

//设置输入字体

public void setFondAndColor(){

field.setFont(new Font("宋体",Font.BOLD,24));

field.setBackground(new Color(100,200,200));

field.setForeground(Color.RED);

//设置字体从右起始

field.setHorizontalAlignment(JTextField.RIGHT);

}

public void showMi(){

frame.pack();

frame.setResizable(false);

frame.setVisible(true);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

public void addEventHander(){

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

allButtons[i].addActionListener(this);

}

clearButton.addActionListener(this);

// backButton.addActionListener(this);

}

@Override

public void actionPerformed(ActionEvent e) {

String str = e.getActionCommand();//取得当前事件返回的值

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

if(x == 0){ //当x为0时表示还没有进行输入

result=str;

sb.append(str);

field.setText(str);

x = 1;

}

else if(x == 1){

result = result +str;

sb.append(str);

field.setText(result);

x = 1;

}

else if(x == 2){

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

result = result+str;

sb.append(str);

field.setText(result);

x = 1;

}

else if(x == 3){

result = str;

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

arrayList.clear();

field.setText(str);

sb.append(str);

field.setText(str);

x = 1;

}

else if(x == 4){

result ="";

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

arrayList.clear();

result = str;

sb.append(str);

field.setText(str);

x = 1;

}

else{

result = result +str;

sb.append(str);

field.setText(result);

x = 1;

}

}

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

if(x == 0){

field.setText("");

x = 2;

}

else if(x == 1){

result = result + str;

arrayList.add(sb.toString());

arrayList.add(str);

sb.append(str);

field.setText(result);

x = 2;

}

else if(x == 2){

x = 2;

}

else if(x == 3){

field.setText(result+str);

arrayList.add(result);

arrayList.add(str);

result = result+str;

x = 2;

}

else if(x == 4){

result ="";

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

arrayList.clear();

x = 2;

}

else{

field.setText(result+str);

arrayList.add(result);

arrayList.add(str);

result = result+str;

x = 2;

}

}

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

if(x == 0){

field.setText("0");

arrayList.clear();

result = "0";

x = 3;

}

else if(x == 1){

try{

arrayList.add(sb.toString());

arrayList = getResult(arrayList);

result = arrayList.get(0);

field.setText(result);

arrayList.clear();

x = 3;

}catch(Exception e1){

field.setText("数据格式异常");

x = 0;

}

}

else if(x == 2){

field.setText("数据格式错误.....");

arrayList.clear();

x = 0;

}

else if(x == 3){

field.setText(result);

x = 3;

}

else if(x == 4){

result ="";

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

arrayList.clear();

x = 3;

}

else {

try{

arrayList.add(sb.toString());

arrayList = getResult(arrayList);

result = arrayList.get(0);

field.setText(result);

arrayList.clear();

x = 3;

}catch(Exception e1){

field.setText("数据格式异常");

x = 0;

}

}

}

else if("CLEAR".equals(str)){

arrayList.clear();

field.setText("0");

arrayList.add("0");

x = 4;

}

else{

if(result.length()1){

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

if(sb.length()0){

sb.delete(sb.length()-1,sb.length());

}

else {

sb.delete(0,1);

}

field.setText(result);

x = 5;

}

else{

result = "";

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

arrayList.clear();

field.setText("0");

x = 0;

}

}

}

public static ArrayListString getResult(ArrayListString list){

String res = null;

String[] s = {"/","*","-","+"};

int i=0;

if(list.size()1){

for(;is.length;){

if(s[i].equals("/")){

for(int j=0;jlist.size();j++){

if(list.get(j).equals(s[i])){

res = Double.toString(Double.parseDouble(list.get(j-1))/Double.parseDouble(list.get(j+1)));

//本地的数据格式

NumberFormat nf = NumberFormat.getInstance();

res = nf.format(Double.parseDouble(res));

res = getChange(res);

list.set(j-1,res);

list.remove(j);

list.remove(j);

getResult(list);

}

}

i++;

}

else if(s[i].equals("*")){

for(int j=0;jlist.size();j++){

if(list.get(j).equals(s[i])){

res = Double.toString(Double.parseDouble(list.get(j-1))*Double.parseDouble(list.get(j+1)));

NumberFormat nf = NumberFormat.getInstance();

res = nf.format(Double.parseDouble(res));

res = getChange(res);

list.set(j-1,res);

list.remove(j);

list.remove(j);

getResult(list);

}

}

i++;

}

else if(s[i].equals("-")){

for(int j=0;jlist.size();j++){

if(list.get(j).equals(s[i])){

res = Double.toString(Double.parseDouble(list.get(j-1))-Double.parseDouble(list.get(j+1)));

NumberFormat nf = NumberFormat.getNumberInstance();

res = nf.format(Double.parseDouble(res));

res = getChange(res);

list.set(j-1,res);

list.remove(j);

list.remove(j);

getResult(list);

}

}

i++;

}

else {

for(int j=0;jlist.size();j++){

if(list.get(j).equals(s[i])){

res = Double.toString(Double.parseDouble(list.get(j-1))+Double.parseDouble(list.get(j+1)));

NumberFormat nf = NumberFormat.getInstance();

res = nf.format(Double.parseDouble(res));

res = getChange(res);

list.set(j-1,res);

list.remove(j);

list.remove(j);

getResult(list);

}

}

i++;

}

}

}

return list;

}

//对数字字符串进行排除不必要符号

public static String getChange(String res){

String s_temp = "";

char[] c = new char[res.length()];

for(int k=0;kc.length;k++){

c[k] = res.charAt(k);

}

for(int k=0;kc.length;k++){

if((c[k]= '0' c[k]= '9')|| c[k] == '.'){

s_temp += c[k];

}

}

return s_temp;

}

public static void main(String[] args){

new CalculatorA().showMi();

}

}

求java工厂模式的一个简单代码例子，尽量简单

这个应该比较简单一点。

某系统日志记录器要求支持多种日志记录方式，如文件记录、数据库记录等，且用户可以根据要求动态选择日志记录方式。现使用工厂方法模式设计该系统,并写出相应Java代码。

interface Log{

public void writeLog();

}

class FileLog implements Log{

public void writeLog(){

System.out.println("文件记录");

}

}

class DatabaseLog implements Log{

public void writeLog(){

System.out.println("数据库记录");

}

}

interface LogFactory{

public Log createLog();

}

class FileLogFactory implements LogFactory{

public Log createLog(){

return new FileLog();

}

}

class DatabaseLogFactory implements LogFactory{

public Log createLog(){

return new DatabaseLog();

}

}

public class Client{

public static void main(String[] args) {

try{

Log log;

LogFactory factory;

//这里可以改成使用DOM和Java反射机制读取XML文件，获取工厂类名

factory=new DatabaseLogFactory ();

log=factory.createLog();

log.writeLog();

}

catch(Exception e){

System.out.println(e.getMessage());

}

}

}

JAVA的一段简单代码

三个类：

计算周长的类：

public class Square {

int length;

Square(int len) {

length = len;

}

void getPerimeter() {

System.out.println("正方形的周长为" + (4 * length));

}

}

计算矩形周长的类：

class Rectangle extends Square {

int width;

Rectangle(int len, int wid) {

super(len);

width = wid;

}

void getPerimeter() {

System.out.println("矩形的周长为" + (2 * (length + width)));

}

}

最后测试main方法类：

public class Calulate {

public Calulate() {

// TODO Auto-generated constructor stub

}

public static void main(String[] args) {

Square sqObj = new Square(15);

sqObj.getPerimeter();

Square rectObj = new Rectangle(10, 33); rectObj.getPerimeter();

}

}

以上就是代码正确的代码了，你可以直接复制到你的计算机上面看看效果，具体的错误原因，我估计是你那里多了个括号、或者是你写的类不规范，继承的话，应该是两个类，那么main 方法可以单独提取出来一个类，这就是面向对象的特性！

路过，希望可以帮助你~