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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。
/**
* 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;
}
}
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();
}
}