List 去重6种

public static void method(List list) {
    // 新集合
    List newList = new ArrayList<>(list.size());
    list.forEach(i -> {
        if (!newList.contains(i)) { // 如果新集合中不存在则插入
            newList.add(i);
        }
    });
    System.out.println("去重集合:" + newList);
}

public static void method_1(List list) {
    Iterator iterator = list.iterator();
    while (iterator.hasNext()) {
        // 获取循环的值
        Integer item = iterator.next();
        // 如果存在两个相同的值
        if (list.indexOf(item) != list.lastIndexOf(item)) {
            // 移除前面那个相同的值
            iterator.remove();
        }
    }
    System.out.println("去重集合:" + list);
}

public static void method_2(List list) {
    HashSet set = new HashSet<>(list);
    System.out.println("去重集合:" + set);
}

public static void method_4(List list) {
    TreeSet set = new TreeSet<>(list);
    System.out.println("去重集合:" + set);
}

public static void method_3(List list) {
    linkedHashSet set = new linkedHashSet<>(list);
    System.out.println("去重集合:" + set);
}

public static void method_5(List list) {
    list = list.stream().distinct().collect(Collectors.toList());
    System.out.println("去重集合:" + list);
}