List a specific element in the first place

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Sometimes there will be such a demand, that is, the list found from the database needs to be processed, such as a list of department members. The product requires you to rank the department manager first. At this time, you can use the built-in tool under the collection tool category. Methods, practices:

You need to traverse the collection to find the position of the element in the collection , and then use the Collections.swap(list,o,i) (O: is the current location of the element, i: is the location to be placed) method to perform the element swap

public static void main(String[] args) {
       List<String> list = Lists.newArrayList();
       list.add("test1");
       list.add("test2");
       list.add("test3");

       System.out.println("更改前：" + JSON.toJSONString(list));

       Collections.swap(list, 1, 0);

       System.out.println("更改后：" + JSON.toJSONString(list));
}