java ArrayList去重复值

方法一：循环元素删除

Java code
// 删除ArrayList中重复元素
public static void removeDuplicate(List list) {
for ( int i = 0 ; i < list.size() - 1 ; i ++ ) {
for ( int j = list.size() - 1 ; j > i; j -- ) {
if (list.get(j).equals(list.get(i))) {
list.remove(j);
}
}
}
System.out.println(list);
}


方法二：通过HashSet剔除

Java code
// 删除ArrayList中重复元素
public static void removeDuplicate(List list) {
HashSet h = new HashSet(list);
list.clear();
list.addAll(h);
System.out.println(list);
}


方法三： 删除ArrayList中重复元素，保持顺序
Java code
// 删除ArrayList中重复元素，保持顺序
public static void 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);
}
list.clear();
list.addAll(newList);
System.out.println( " remove duplicate " + list);