java中数组怎么去重

统一输入

    public static List createList(){
        List list = new ArrayList();
        list.add(1);
        list.add(10);
        list.add(10);
        list.add(2);
        list.add(2);
        list.add(3);
        list.add(3);
        list.add(3);
        list.add(4);
        list.add(5);
        return list;
    }

通过set中元素不重复的特性进行去重

• 去除重复数据
• 不会保持原来的顺序

public static void distinct1(List list) {
    final boolean sta = null != list && list.size() > 0;
    List doubleList= new ArrayList();
    if (sta) {
        Set set = new HashSet();
        set.addAll(list);
        doubleList.addAll(set);
    }
    System.out.println(doubleList);
}

[1, 2, 3, 4, 5, 10]

LinkedHashSet集合

• 去除重复元素
• 保持原有顺序

public static void distinct2(List list) {
    LinkedHashSet<Integer> linkedHashSet = new LinkedHashSet<>(list);
    ArrayList<Integer> listWithoutDuplicates = new ArrayList<>(linkedHashSet);
    System.out.println(listWithoutDuplicates);
}
[1, 10, 2, 3, 4, 5]

TreeSet集合

• 去除重复
• 不保持原有顺序

public static void distinct3(List list){
    List listNew = new ArrayList<>(new TreeSet<>(list));
    System.out.println(listNew);
}
[1, 2, 3, 4, 5, 10]

遍历List集合,将元素添加到另一个List集合中

• 去除重复元素
• 保持原有顺序

public static void distinct4(List list) {
    List  listNew = new ArrayList<>();
    for (Object o : list) {
        if(!listNew.contains(o)){
            listNew.add(o);
        }
    }
    System.out.println(listNew);
}
[1, 10, 2, 3, 4, 5]

java8新特性stream

• 去除重复元素
• 保持原有顺序

public static void distinct5(List list){
    List myList = (List) list.stream().distinct().collect(Collectors.toList());
    System.out.println(myList);
}
[1, 10, 2, 3, 4, 5]

双重for循环

• 去除重复元素
• 保持原有顺序

public static void distinct6(List list){
    for (int i = 0; i < list.size(); i++) {
        for (int j = i + 1; j < list.size(); j++) {
            if (list.get(i) == list.get(j)) {
                list.remove(j);
                j--;
            }
        }
    }
    System.out.println(list);
}
[1, 10, 2, 3, 4, 5]