Java代码可以超过2000行

以1000行为准，超过千行就要考虑类拆分了。

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对于经常使用的java类，代码行数应该尽可能的少，这样能减少java类的加载时间，减少内存频繁占用和回收。如果类过大，java类加载会耗时并且占用内存大。容易引起内存回收。

如果前期准备得当，设计，建模合理。一般来说，每个类的代码就不会很多，几百行。很早之前看过有前辈说，300行之内。

急求大神发几个java 300行代码的小程序 简单点的

/**

* 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;

}

}

如何用JAVA语言编写计算器小程序？

具体代码如下：

import javax.swing.*;

import java.awt.event.*;

import java.awt.*;

public class Calculator  extends JFrame implements ActionListener  {

private JFrame jf;

private JButton[] allButtons;

private JButton clearButton;

private JTextField jtf;

public Calculator() {

//对图形组件实例化

jf=new JFrame("任静的计算器1.0：JAVA版");

jf.addWindowListener(new WindowAdapter(){

public void windowClosing(){

System.exit(0);

}

});

allButtons=new JButton[16];

clearButton=new JButton("清除");

jtf=new JTextField(25);

jtf.setEditable(false);

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

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

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

}

}

public void init(){

//完成布局

jf.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(jtf);

for(int i=0;i16;i++){

centerPanel.add(allButtons[i]);

}

southPanel.add(clearButton);

jf.add(northPanel,BorderLayout.NORTH);

jf.add(centerPanel,BorderLayout.CENTER);

jf.add(southPanel,BorderLayout.SOUTH);

addEventHandler();

}

//添加事件监听

public void addEventHandler(){

jtf.addActionListener(this);

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

allButtons[i].addActionListener(this);

}

clearButton.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e) {

// TODO Auto-generated method stub

Calculator.this.jtf.setText("");

}

});

}

//事件处理

public void actionPerformed(ActionEvent e) {

//在这里完成事件处理  使计算器可以运行

String action=e.getActionCommand();

if(action=="+"||action=="-"||action=="*"||action=="/"){

}

}

public void setFontAndColor(){

Font f=new Font("宋体",Font.BOLD,24);

jtf.setFont(f);

jtf.setBackground(new Color(0x8f,0xa0,0xfb));

for(int i=0;i16;i++){

allButtons[i].setFont(f);

allButtons[i].setForeground(Color.RED);

}

}

public void showMe(){

init();

setFontAndColor();

jf.pack();

jf.setVisible(true);

jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

public static void main(String[] args){

new Calculator().showMe();

}

}