用ArrayList实现用户信息的添加，删除，更新，查询

      package jpack;
import java.util.*;
import   java.io.*; 
public class Usermanage {

     ArrayList a = new ArrayList();
     User u= new User();
     boolean singal=true;
   	 public void addUser()throws IOException
	 {
		   System.out.print("输入要添加的ID:");
		   BufferedReader In=new BufferedReader(new InputStreamReader(System.in));
		   String Id=In.readLine();
		   System.out.print("输入要添加的Name:");
		   String Name=In.readLine();
		   System.out.print("输入要添加的Password:");
		   String Pass=In.readLine();
		   User u = new User(Id,Name, Pass);
		   a.add(u);
	}

	
    public void display()
	{
		
		   Iterator   i=a.iterator();   
		   while(i.hasNext()){ 
			  User u=(User)(i.next());//把它转换为自己的对象
			  System.out.println("序列表的内容为： "+"ID:   "+u.ID +"  "+"name:  "+u.name+"  "+ "password:  "+ u.password);   
		  }  
	}
   
   
    public  void delete(List<User>a,String c,String b)
	{
		  for(int i=0;i<a.size();i++)
		  {
			User p=(User)a.get(i);
			if(c.equals("a"))
			{
				if(p.getName().equals(b))
				   a.remove(p);
			}
			if( c.equals("b"))
			{
				if(p.getId().equals(b))
					a.remove(i);
			}	
		}		
	}

     
            
    public void del()throws IOException
     {
	   System.out.print("输入要删除的ID:");
	   BufferedReader In=new BufferedReader(new InputStreamReader(System.in));
	   String Id=In.readLine();
		for(int i=0;i<a.size();i++)
		{
			User p=(User)a.get(i);
		    if(p.getId().equals(Id))
			{
		    	System.out.println("此ID号对应的信息为："+"ID:　 " +p.getId()+"  "+ "name:  "+ p.getName()+"  "+ "password  "+p.getPassword() );
				System.out.println("确认是否删除此记录，是输入Y,否则输入N:");
				String Iden=In.readLine();
				{
					if(Iden.equals("Y"))
					      a.remove(i);
					//else 
						  //  break;
				}
					 singal=false;
					
				}
		 }
		 if(singal)
	         System.out.println("无你要删除的ID信息！");
     	}
										
   
    public void  Update()throws IOException
    {
 		System.out.print("输入要更新的ID:");
 	    BufferedReader In=new BufferedReader(new InputStreamReader(System.in));
 	    String Id=In.readLine();
 	    for(int i=0;i<a.size();i++)
 		{
 			    User p=(User)a.get(i);
 				if(p.getId().equals(Id))
 				 {
 					System.out.print("输入要更新后的ID:");
 				    String id=In.readLine();
 	                p.ID= id;
		                System.out.print("输入要添加的Name:");
		                String Name=In.readLine();
		                p.name = Name;
		                System.out.print("输入要添加的Password:");
		                String Pass=In.readLine();
		                p.password = Pass;
 				    singal=false;
					  
        		  }
 				}
 	    if(singal)
 	         System.out.println("无你要找更新的ID信息！");
    }
    
    
    
    
    public void searchById()throws IOException
        {
    	     System.out.print("输入要查询的ID:");
	         BufferedReader In=new BufferedReader(new InputStreamReader(System.in));
	         String Id=In.readLine();
	         boolean singal=true;
	         for(int i=0;i<a.size();i++)
		     {
			    User p=(User)a.get(i);
				if(p.getId().equals(Id))
				{ 
					System.out.println("此ID对应的信息为："+"ID: "+p.getId()+"  "+ "name: "+ p.getName()+"  "+ "password: "+p.getPassword() );
				    singal=false;
                  }
			  }
	         if(singal)
	         System.out.println("无你要找的ID信息！");
	          else return;
	         }

			
        
       
       public void searchByNameExact()throws IOException
       {
         	System.out.print("输入要查询的Name:");
	        BufferedReader In=new BufferedReader(new InputStreamReader(System.in));
	        String Name=In.readLine();
	        for(int i=0;i<a.size();i++)
		    {
			    User p=(User)a.get(i);
				if(p.getName().equals(Name))
				{ 
					System.out.println("此Name对应的信息为："+"ID: "+p.getId()+"  "+ "name: "+ p.getName()+"  "+ "password: "+p.getPassword() );
				    singal=false;
					
				}
				}
	       if(singal)
	         System.out.println("无你要找的Name信息！");
       }
		
       
       
    
      public void  searchByNameSimple()throws IOException
       {
		    System.out.print("输入要查询的Name:");
	        BufferedReader In=new BufferedReader(new InputStreamReader(System.in));
	        String Name=In.readLine();
	        for(int i=0;i<a.size();i++)
		    {
			    User p=(User)a.get(i);
				if(p.getName().contains(Name))
					{
					   System.out.println("此Name对应的信息为："+"ID: "+p.getId()+"  "+ "name: "+ p.getName()+"  "+ "password: "+p.getPassword() );
				        singal=false;
				    }
		    }
	        if(singal)
                   System.out.println("无你要查询的Name的信息！");
                     
}
      
}