利用Iterator删除List里相近或相同的对象

package com.eg.log;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.log4j.Logger;

public class TestLog
{
 private static Logger log = Logger.getLogger(TestLog.class);

 /**
  * @param args
  */
 public static void main(String[] args)
 {
  List<User> users = new ArrayList<User>();
  User user5 = new User("yff","111111111","111111111");
  User user9 = new User("yff","111111111","111000");
  User user1 = new User("yff","111111111","111");
  User user6 = new User("lxx","222222222","222222222");
  User user2 = new User("lxx","222222222","222");
  User user3 = new User("stt","333333333","333111");
  User user7 = new User("stt","333333333","333");
  User user4 = new User("jqq","444444444","444444444");
  User user8 = new User("jqq","444444444","444");
  User user10 = new User("ltt","55555555","555");
  users.add(user5);
  users.add(user9);
  users.add(user1);
  users.add(user6);
  users.add(user2);
  users.add(user3);
  users.add(user7);
  users.add(user4);
  users.add(user8);
  users.add(user10);
  List<User> users2 = new ArrayList<User>();
  users2.addAll(users);
  
  for(User user:users){
   System.out.println(user.toString());
  }
  System.out.println("------------------------------------------");
  
  for(User user11 : users)
  {
   for(Iterator<User> userIt2 = users2.iterator();userIt2.hasNext();)
   {
    User user12 = userIt2.next();
    if(user11.getUsername().equals(user12.getUsername()))
    {
     if(user11.getGrade().length()>user12.getGrade().length())
     {
      userIt2.remove();
     }
    }
    
   }
  }
  
  for(User user:users2){
   System.out.println(user.toString());
  }
 }
 

}
class User{
 public User(){
  
 }
 public User(String username,String address,String grade){
  this.username=username;
  this.address=address;
  this.grade=grade;
 }
 public String username;
 public String address;
 public String grade;
 public String getUsername() {
  return username;
 }
 public String getGrade() {
  return grade;
 }
 public void setGrade(String grade) {
  this.grade = grade;
 }
 public void setUsername(String username) {
  this.username = username;
 }
 public String getAddress() {
  return address;
 }
 public void setAddress(String address) {
  this.address = address;
 }
 public String toString()
 {
  return this.username+"--"+this.address+"---"+this.grade;
 }
}