List集合去除重複數據的方法

• 循環list中的全部元素而後刪除重複

public static List 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);
			}
		}
	}
	return list;
}

 

• 經過HashSet踢除重複元素

public static List removeDuplicate(List list) {   
    HashSet h = new HashSet(list);   
    list.clear();   
    list.addAll(h);   
    return list;   
}

 

• 刪除ArrayList中重複元素，保持順序

// 刪除ArrayList中重複元素，保持順序
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);
}

 

• 把list裏的對象遍歷一遍，用list.contain()，若是不存在就放入到另一個list集合中

public static List removeDuplicate(List list) {
	List listTemp = new ArrayList();
	for (int i = 0; i < list.size(); i++) {
		if (!listTemp.contains(list.get(i))) {
			listTemp.add(list.get(i));
		}
	}
	return listTemp;
}