利用了Set不重复的特性

方法一：

public static List removeDuplicateWithOrder(List list) {

Set set = new HashSet();

List newList = new ArrayList();

for (Iterator iter = list.iterator(); iter.hasNext();) {

Object element = iter.next();

if (set.add(element))

newList.add(element);

}

return newList;

}

方法二：

public static List removeDuplicate(List list)

{

Set set = new LinkedHashSet();

set.addAll(list);

list.clear();

list.addAll(set);

return list;

}

方法三：

import java.util.*;

class sigleE

{

public static void main(String[] args)

{

ArrayList al = new ArrayList();

al.add("java1");

al.add("java2");

al.add("java1");

al.add("java3");

System.out.println(al);

al = list(al);

System.out.println(al);

}

public static ArrayList list(ArrayList al)

{

ArrayList newal = new ArrayList();//新建一个中间集合

for(Iterator it = al.iterator();it.hasNext();)//集合循环

{

Object obj = it.next();

if(!newal.contains(obj))//不包含重复的输出

newal.add(obj);

}

return newal;

}

}