java ArrayList去重复值

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;

}

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public static List removeDuplicateWithOrder(List list) {
Set set = new HashSet(list.size());
set.addAll(list);
List newList = new ArrayList(set.size());
newList.addAll(set);
return newList;
}

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public static List removeDuplicateWithOrder(List list) { 
        List newList = new ArrayList(); 
        for (Object o : list) { 
            if (!newList .contains(o)) newList.add(o); 
        } 
        return newList; 
    }