用Java完成一个控制台的学生管理系统，实现增删改查。

Student

public class Student {          
	private String sid;
	private String name;
	private String age;
	private String address;
	public Student() {
	}
	public Student(String sid,String name,String age,String adress) 
	{
		this.sid=sid;
		this.name=name;
		this.age=age;
		this.address=adress;
	}
	public String getSid() {
		return sid;
	}
	public void setSid(String sid) {
		this.sid = sid;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getAge() {
		return age;
	}
	public void setAge(String age) {
		this.age = age;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}

}

StudentManager

import java.util.Scanner;
import java.util.ArrayList;

public class StudentManager {
	public static void main(String[] args)
	{
		ArrayList<Student> array=new ArrayList <Student>();
		while(true) {
		System.out.println("-----欢迎来到学生管理系统-----");
		System.out.println("1 添加学生");
		System.out.println("2 删除学生");
		System.out.println("3 修改学生");
		System.out.println("4 查看所有学生");
		System.out.println("5 退出");
		System.out.println("请输入你的选择：");
		
		Scanner sc=new Scanner(System.in);
		String line =sc.nextLine();
		
		switch(line) {
		case "1":
			 //  System.out.println("添加学生");
			addStudent(array);
		       break;
		case "2":
			   //System.out.println("删除学生");
			deleteStudent(array);
		       break;
		case "3":
			   //System.out.println("修改学生");
		      updateStudent(array);
			break;
		case "4":
			  // System.out.println("查看所有学生");
		     findAllStudent(array);
			break;
		case "5":
			   System.out.println("谢谢使用");
		System.exit(0);
		    
		}
	}
}	

   public static void addStudent(ArrayList<Student>array) {
	   Scanner sc=new Scanner(System.in);
	   String sid;
	   while (true) 
	   {
	   System.out.println("请输入学生学号：");
	   sid=sc.nextLine();
	   boolean flag=isUsed(array,sid);
	   if(flag)
	   {
		   System.out.println("你输入的学号已经被使用，请重新输入");
	   }else {
		   break;
	   }
	   }  
	   System.out.println("请输入学生姓名：");
	   String name=sc.nextLine();
	   System.out.println("请输入学生年龄：");
	   String age=sc.nextLine();
	   System.out.println("请输入学生居住地：");
	   String address=sc.nextLine();
 
	   Student s=new Student();
	   s.setSid(sid);
	   s.setName(name);
	   s.setAge(age);
	   s.setAddress(address);
	   
	   array.add(s);
	   System.out.println("添加学生成功！");
   }
   public static boolean isUsed(ArrayList<Student> array,String sid)
   {
	   boolean flag=false;
	   for(int i=0;i<array.size();i++)
	   {
		   Student s= array.get(i);
		   flag=true;
		   break;
	   }
   return flag;
}
public static void findAllStudent(ArrayList<Student> array)
{
	if(array.size()==0) {
		System.out.println("无信息，请添加信息再查询");
		return;
	}
	System.out.println("学号\t姓名\t年龄\t居住地");
    for(int i=0;i<array.size();i++) {
    	Student s= array.get(i);
    	System.out.println(s.getSid()+"\t"+s.getName()+"\t"+s.getAge()+"岁\t"+s.getAddress());
    }
}	
public static void deleteStudent(ArrayList<Student> array)
{
	Scanner sc=new Scanner(System.in);
	System.out.println("请输入你要删除的学生的学号");
	String sid=sc.nextLine();
	int index=-1;
	for(int i=0;i<array.size();i++)
	{
		Student s=array.get(i);
		if(s.getSid().equals(sid))
		{
		index=i;
			break;
		}
	}
	if(index == -1)
	{
		System.out.println("该信息不存在，请重新输入！");
	}
		else {
			array.remove(index);
	
	System.out.println("删除学生成功");
		}
}
public static void updateStudent(ArrayList<Student> array)
{
	Scanner sc=new Scanner(System.in);
	System.out.println("请输入你需要修改的学生的学号");
	String sid=sc.nextLine();
	int index=-1;
	for(int i=0;i<array.size();i++)
	{
		Student s=array.get(i);
		if(s.getSid().equals(sid))
		{
		index=i;
			break;
		}
	}
	if(index == -1)
	{
		System.out.println("该信息不存在，请重新输入！");
	}
		else {
			array.remove(index);

	System.out.println("请输入学生新姓名：");
	String name=sc.nextLine();
	System.out.println("请输入学生新年龄：");
    String age=sc.nextLine(); 
    System.out.println("请输入学生新居住地：");
    String address=sc.nextLine();
    
    Student s=new Student();
    s.setSid(sid);
    s.setName(name);
    s.setAge(age);
    s.setAddress(address);
    for(int i=0;i<array.size();i++)
    {
    	Student student=array.get(i);
    	if(student.getSid().equals(sid))
    	{
    		array.set(i,s);
    		break;
    	}
    }
    	System.out.println("修改学生成功！");
    }
}
}