清除(ArrayList)集合中重复元素

需求：编写一个函数清除（ArrayList）集合中重复元素，如果书号是一样的就视为重复元素。

        方式1：get

        方式2：迭代器 

package com.cn.list;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* Author：Liu Zhiyong
* Version：Version_1
* Date：2016年7月14日12:43:48
* Desc：需求：编写一个函数清除集合中重复元素，如果书号是一样的就视为重复元素。
*/
class Book{
int id;
String name;
public Book(int id, String name) {
 this.id = id;
this.name = name;
}
@Override
public boolean equals(Object obj) {
// TODO Auto-generated method stub
Book b = (Book)obj;
return this.id == b.id;
}
@Override
public int hashCode() {
// TODO Auto-generated method stub
return this.id;
}
}
public class Demo6 {
public static void main(String[] args) {
ArrayList list2 = new ArrayList();
list2.add(new Book(110, "java编程思想"));
list2.add(new Book(120, "java核心技术"));
list2.add(new Book(130, "深入JavaWEB"));
list2.add(new Book(110, "jsp"));
list2.add(new Book(140, "javaScript"));
list2.add(new Book(150, "javaee"));
list2.add(new Book(120, "java核心技术大全"));
ArrayList list = clearRepeat3(list2);
//ArrayList list = clearRepeat2(list2);
//ArrayList list = clearRepeat1(list2);
printList(list);
}
//遍历结合输出
public static void printList(ArrayList list) {
Iterator iterator = list.iterator();
while(iterator.hasNext()){
Book b = (Book)iterator.next();
System.out.println(b.id + "\t" + b.name);
}
}
public static ArrayList clearRepeat1(ArrayList list){
//创建一个新的集合
ArrayList newList = new ArrayList();
//获取迭代器
Iterator iterator = list.iterator();
while(iterator.hasNext()){
Book b = (Book)iterator.next();//从旧集合中获取的元素
Iterator iterator2 = newList.iterator();
boolean flag = true;
while(iterator2.hasNext()){
Book b2 = (Book)iterator2.next();//获取新集合中的元素
if(b.id == b2.id){
flag = false;
}
}
if(flag)
newList.add(b);
}
return newList;
}
//get方法
public static ArrayList clearRepeat2(List list2) {
ArrayList list = new ArrayList();
for(int i=0; i<list2.size(); i++){
Book b2 = (Book)list2.get(i);
boolean flag = true;
for(int j=0; j<list.size(); j++){
Book b = (Book)list.get(j);
if(b2.id == b.id){
flag = false;
}
}
if(flag){
list.add(list2.get(i));
}
}
return list;
}
//迭代器
public static ArrayList clearRepeat3(ArrayList list2) {
ArrayList list = new ArrayList();
Iterator iterator = list2.iterator();
while(iterator.hasNext()){
Book b = (Book)iterator.next();
if(!list.contains(b)){//这里比较的是id是否相同，所以要重写equals方法（和hashCode方法）
list.add(b);
}
}
return list;
}
}