这个计算器可是我自己写了好几天才写好的耶，你能在网上找到？
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计算器：
// Calculator.java
public class Calculator {
private static final char NO_OP = '\0';
private static final char PLUS = '+';
private static final char SUBTRACT = '-';
private static final char MULTIPLY = '*';
private static final char DIVIDE = '/';
private float number1 = 0.0F;
//private float number2 = Float.NaN;
private char operator = NO_OP;
//等于运算
public String opEquals(String number) {
float result;
if ( operator == NO_OP ) {
result = parseNumber(number);
} else {
result = performOperation(parseNumber(number));
}
operator = NO_OP;
number1 = result;
return Float.toString(result);
}
//加法运算
public String opAdd(String number) {
float result;
if ( operator == NO_OP ) {
result = parseNumber(number);
} else {
result = performOperation(parseNumber(number));
}
operator = PLUS;
number1 = result;
return Float.toString(result);
}
//减法运算
public String opSubtract(String number) {
float result;
if ( operator == NO_OP ) {
result = parseNumber(number);
} else {
result = performOperation(parseNumber(number));
}
operator = SUBTRACT;
number1 = result;
return Float.toString(result);
}
//乘法运算
public String opMultiply(String number) {
float result;
if ( operator == NO_OP ) {
result = parseNumber(number);
} else {
result = performOperation(parseNumber(number));
}
operator = MULTIPLY;
number1 = result;
return Float.toString(result);
}
//除法运算
public String opDivide(String number) {
float result;
if ( operator == NO_OP ) {
result = parseNumber(number);
} else {
result = performOperation(parseNumber(number));
}
operator = DIVIDE;
number1 = result;
return Float.toString(result);
}
//处理运算符
private float performOperation(float number2) {
float result = 0.0F;
switch ( operator ) {
case PLUS:
result = number1 + number2;
break;
case SUBTRACT:
result = number1 - number2;
break;
case MULTIPLY:
result = number1 * number2;
break;
case DIVIDE:
result = number1 / number2;
break;
}
return result;
}
//将字符串类型转换为浮点型
private static float parseNumber(String number) {
float real_number;
try {
real_number = Float.parseFloat(number);
} catch (NumberFormatException e) {
real_number = Float.NaN;
}
return real_number;
}
}
GUI程序：
// CalculatorGUI.java
import java.awt.*;
import java.awt.event.*;
public class CalculatorGUI {
// 定义按钮
private Button key0, key1, key2, key3, key4;
private Button key5, key6, key7, key8, key9;
private Button keyequal, keyplus, keyminus;
private Button keyperiod, keymult, keydiv;
// 定义存放按钮的区域
private Panel buttonArea;
// 定义存放运算结果的区域
private Label answer;
// 用来实现运算功能的类的对象实例化
private Calculator calculator;
private boolean readyForNextNumber;
public CalculatorGUI() {
calculator = new Calculator();
readyForNextNumber = true;
answer = new Label("0.0",Label.RIGHT);
key0 = new Button("0");
key1 = new Button("1");
key2 = new Button("2");
key3 = new Button("3");
key4 = new Button("4");
key5 = new Button("5");
key6 = new Button("6");
key7 = new Button("7");
key8 = new Button("8");
key9 = new Button("9");
keyequal = new Button("=");
keyplus = new Button("+");
keyminus = new Button("-");
keymult = new Button("*");
keydiv = new Button("/");
keyperiod = new Button(".");
buttonArea = new Panel();
}
public void launchFrame() {
buttonArea.setLayout(new GridLayout(4,4));
buttonArea.add(key7);
buttonArea.add(key8);
buttonArea.add(key9);
buttonArea.add(keyplus);
buttonArea.add(key4);
buttonArea.add(key5);
buttonArea.add(key6);
buttonArea.add(keyminus);
buttonArea.add(key1);
buttonArea.add(key2);
buttonArea.add(key3);
buttonArea.add(keymult);
buttonArea.add(key0);
buttonArea.add(keyperiod);
buttonArea.add(keyequal);
buttonArea.add(keydiv);
// 设置事件接收句柄
OpButtonHanlder op_handler = new OpButtonHanlder();
NumberButtonHanlder number_handler = new NumberButtonHanlder();
key0.addActionListener(number_handler);
key1.addActionListener(number_handler);
key2.addActionListener(number_handler);
key3.addActionListener(number_handler);
key4.addActionListener(number_handler);
key5.addActionListener(number_handler);
key6.addActionListener(number_handler);
key7.addActionListener(number_handler);
key8.addActionListener(number_handler);
key9.addActionListener(number_handler);
keyperiod.addActionListener(number_handler);
keyplus.addActionListener(op_handler);
keyminus.addActionListener(op_handler);
keymult.addActionListener(op_handler);
keydiv.addActionListener(op_handler);
keyequal.addActionListener(op_handler);
// 新建一个帧，并且加上消息监听
Frame f = new Frame("计算器");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
f.setSize(200, 200);
f.add(answer, BorderLayout.NORTH);
f.add(buttonArea, BorderLayout.CENTER);
f.setVisible (true);
}
//响应按钮事件，并根据不同的按钮事件进行不同的运算
private class OpButtonHanlder implements ActionListener {
public void actionPerformed(ActionEvent event) {
char operator = event.getActionCommand().charAt(0);
String result = "";
switch ( operator ) {
case '+':
result = calculator.opAdd(answer.getText());
break;
case '-':
result = calculator.opSubtract(answer.getText());
break;
case '*':
result = calculator.opMultiply(answer.getText());
break;
case '/':
result = calculator.opDivide(answer.getText());
break;
case '=':
result = calculator.opEquals(answer.getText());
break;
}
answer.setText(result);
readyForNextNumber = true;
}
}
//处理连续运算时主界面的显示
private class NumberButtonHanlder implements ActionListener {
public void actionPerformed(ActionEvent event) {
if ( readyForNextNumber ) {
answer.setText(event.getActionCommand());
readyForNextNumber = false;
} else {
answer.setText(answer.getText() + event.getActionCommand().charAt(0));
}
}
}
//主函数，也是该应用程序的执行入口处
public static void main(String[] args) {
CalculatorGUI calcGUI = new CalculatorGUI();
calcGUI.launchFrame();
}
}
注意：运行的是GUI程序
优秀的JAVA程序员平常一天至少写150行代码，普通的JAVA程序员,平均一天的有效代码量大概是50~70行, 注意是有效代码。
延展回答:
JAVA程序员广义上是指一群以JAVA为谋生手段的软件开发人员。狭义的说，是指拥有SUN公司JAVA认证的程序员。Sun Java认证分为两个级别：Sun 认证Java程序员和Sun 认证Java开发员。通常要求程序员精通java基础，java高级编程，及常用java设计模式，并深入理解mvc编程模式，了解uml相关知识。
虽然JAVA人才的薪水很高，但是对该类人才需求旺盛的IT企业却很难招聘到合格的JAVA人员。其中，最根本的原因就是许多计算机专业的毕业生在读期间没有掌握实用的技能与经验，距离企业的实际用人需求有较大的差距。因此，计算机专业的大学生欲成为Java程序员，最便捷的一条路就是参加以实战项目为主要教学方法的JAVA职业技能培训，从而有效地缩短同企业具体用人需求之间的差距。
Java平台以其移动性、安全性和开放性受到追捧。据IDC预计，自2001年起的其后5年内，采用Java的IT产品的价值将翻番，在2006年将达到4.53亿美元，年增长率为14.9%。截止到2003年5月，Java注册开发商超过300万人，对JRE(Java运行环境)的下载达7200万次。詹姆斯·戈士林博士预计在3～5年内Java技术开发商将发展到1000万。无线Java也在迅速攀升。
/**
* 文件名：Operation.java 2014-1-2 下午3:06:37
* @author Administrator
*/
package cc.icoc.javaxu.action;
import java.util.ArrayList;
import java.util.Scanner;
import cc.icoc.javaxu.datas.StudentInfo;
/**
* @author 许仕永
* 创建时间: 2014 2014-1-2 下午3:06:37
*/
public class Operation
{
int stuNo,stuAge;
String stuName,stuClass,stuSex;
ArrayListStudentInfo list;
/**程序入口
* @param args
*/
public static void main(String[] args)
{
// TODO Auto-generated method stub
new Operation().operation();
}
private int inputInt()
{
Scanner scanner = new Scanner(System.in);
return scanner.nextInt();
}
private String inputStr()
{
Scanner scanner = new Scanner(System.in);
return scanner.nextLine();
}
private void operation()
{
// TODO Auto-generated method stub
if(list == null)
{
list = new ArrayListStudentInfo();
}
while(true)
{
System.out.println("\t\t\t学生信息管理系统\n");
System.out.println("1.信息查阅");
System.out.println("2.信息查询");
System.out.println("3.信息录入");
System.out.println("4.退出系统");
int what = inputInt();
if ( what == 1 )
{
getInfo();
} else if ( what == 2 )
{
allSerach();
} else if ( what == 3 )
{
inputInfo();
} else if( what == 4 )
{
System.out.println("已经退出系统");
System.exit(0);
}
}
}
/**
* 获取全部学生的信息列表
*/
private void getInfo()
{
if(!list.isEmpty())
{
for ( int i = 0; i list.size(); i++ )
{
System.out.println(list.get(i));
}
}
}
/**
* 执行查找
*/
private void allSerach()
{
System.out.println("1.输入学号进行查询");
System.out.println("2.输入姓名进行查询");
int what = inputInt();
if(what == 1)
{
System.out.println("请输入学号：");
search(inputInt());
}
else
{
System.out.println("请输入姓名：");
search(inputStr());
}
}
/**
* 按学生姓名查询学生信息
* @param name 学生姓名
*/
private StudentInfo search(String name)
{
for ( int i = 0; i list.size(); i++ )
{
if(list.get(i).getStuName().equals(name))
{
System.out.println(list.get(i));
return list.get(i);
}
}
System.out.println("未查询到该名字的学生");
return null;
}
/**
* 按学号查询学生信息
* @param id 学号
*/
private StudentInfo search(int id)
{
for ( int i = 0; i list.size(); i++ )
{
if(list.get(i).getStuNo()==id)
{
System.out.println(list.get(i));
return list.get(i);
}
}
System.out.println("未查询到该学号的学生");
return null;
}
/**
* 录入学生信息
*/
private void inputInfo()
{
try
{
System.out.print("请输入学生学号：\n");
stuNo = inputInt();
System.out.print("请输入学生姓名：\n");
stuName = inputStr();
System.out.print("请输入学生性别：\n");
stuSex = inputStr();
System.out.print("请输入学生年龄：\n");
stuAge = inputInt();
System.out.print("请输入学生班级：\n");
stuClass = inputStr();
list.add(new StudentInfo(stuNo, stuAge, stuName, stuSex, stuClass));
} catch (Exception e)
{
// TODO: handle exception
System.out.println("不允许为空，请重新输入");
}
}
}
package cc.icoc.javaxu.action;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Stu
{
int countStu = 0;
int sum = 0;
int avg = 0;
ListStuBean list = new ArrayListStu.StuBean();
public static void main(String[] args)
{
new Stu().go();
}
private void go()
{
A:while(true)
{
//构造实体Bean来存储学生成绩
StuBean bean = new StuBean();
System.out.println("请输入成绩：");
System.out.println("语文：");
bean.setYuwen(scanner());
System.out.println("数学：");
bean.setMath(scanner());
//获取英语成绩
System.out.println("英语：");
bean.setEnglish(scanner());
//存入容器
list.add(bean);
for ( int i = 0; i list.size(); i++ )
{
sum += list.get(i).english+list.get(i).math+list.get(i).yuwen;
}
avg = sum / (3*list.size());
System.out.println("当前有"+list.size()+"条学生记录，所有学生总分="+sum+"平均分为"+avg);
//输入y继续录入学生信息，输入x退出
System.out.println("\n已成功录入一个学生的数据，是否继续/退出(y/x)");
if("x".equals(scannerString()))
break A;
}
}
/**输入*/
private int scanner()
{
Scanner scanner = new Scanner(System.in);
return scanner.nextInt();
}
/**输入*/
private String scannerString()
{
Scanner scanner = new Scanner(System.in);
return scanner.nextLine();
}
class StuBean
{
int math;
int yuwen;
int english;
public int getMath()
{
return math;
}
public void setMath(int math)
{
this.math = math;
}
public int getYuwen()
{
return yuwen;
}
public void setYuwen(int yuwen)
{
this.yuwen = yuwen;
}
public int getEnglish()
{
return english;
}
public void setEnglish(int english)
{
this.english = english;
}
}
}
/**
* 文件名：StudentInfo.java 2014-1-2 下午3:07:29
* @author Administrator
*/
package cc.icoc.javaxu.datas;
/**
* @author 许仕永
* 创建时间: 2014 2014-1-2 下午3:07:29
*/
public class StudentInfo
{
int stuNo,stuAge;
String stuName,stuSex,stuClass;
public StudentInfo(int stuNo, int stuAge, String stuName, String stuSex, String stuClass)
{
super();
this.stuNo = stuNo;
this.stuAge = stuAge;
this.stuName = stuName;
this.stuSex = stuSex;
this.stuClass = stuClass;
}
public int getStuNo()
{
return stuNo;
}
public void setStuNo(int stuNo)
{
this.stuNo = stuNo;
}
public int getStuAge()
{
return stuAge;
}
public void setStuAge(int stuAge)
{
this.stuAge = stuAge;
}
public String getStuName()
{
return stuName;
}
public void setStuName(String stuName)
{
this.stuName = stuName;
}
public String getStuSex()
{
return stuSex;
}
public void setStuSex(String stuSex)
{
this.stuSex = stuSex;
}
public String getStuClass()
{
return stuClass;
}
public void setStuClass(String stuClass)
{
this.stuClass = stuClass;
}
@Override
public String toString()
{
// TODO Auto-generated method stub
String s = "学号："+getStuNo()+"\t姓名："+getStuName()+" \t性别："+getStuSex()+"\t年龄："+getStuAge()+"\t班级："+getStuClass();
return s;
}
}
