Precautions for using remove in arraylist in Java

From: http://blog.sina.com.cn/s/blog_4914a33b0100xtyj.html

// When removing a message,
The size of arraylist has changed (that is, list. Size () has changed );
When I is greater than or equal to list. Size (), the loop jumps out, And the arraylist can no longer be executed;
So you must execute I --, that is, I = I-1;
Now we can traverse all the information in the list. You cannot use the remove feature in the iterator traversal. An exception is thrown. (Java. util. concurrentmodificationexception; At java. util. arraylist $ arraylistiterator. Next)

Public class trickyal {

 

 
    Publicstatic upload list <user> LlU = newclientlist <user> ();
    Publicstatic hashmap <string, user> hmu = newhashmap <string, user> ();
    Publicstatic arraylist <user> ulist = newarraylist <user> (arrays. aslist
    (Newuser [] {
           
            New User (2, "Eric "),
            New User (3, "Eric "),
            New User (1, "Aaron "),
            New User (4, "Eric ")
   
    }
    ));
      Static {
            LlU. Add (new user (1, "Aaron "));
            LlU. Add (new user (2, "Eric "));
            LlU. Add (new user (3, "Tom "));
            Hmu. Put ("1", new user (3, "Tom "));
            Hmu. Put ("2", new user (2, "Eric "));
            Hmu. Put ("3", new user (1, "Leo "));
            Hmu. Put ("3", new user (4, "Scott "));
           
           
    }
    Publicstatic voiddeleteuser (arraylist <user> urlist, string auser ){
           
            Iterator itr = urlist. iterator ();
            Int c = urlist. Size ();
           
            For (INT I = 0; I <C; I ++ ){
                  If (auser. Equals (urlist. Get (I). Name )){
                        Urlist. Remove (I );
                        I --;
                        C --;
                  }
            }
           
           
    }
Public static voiddeleteuser (partition list <user> urlist, string auser ){
           
            Iterator itr = urlist. iterator ();
            Int c = urlist. Size ();