//set集合去重，不改變原有的順序
    public static void pastLeep1(List<String> list){
        System.out.println("list = [" + list.toString() + "]");
        List<String> listNew=new ArrayList<>();
        Set set=new HashSet();
        for (String str:list) {
            if(set.add(str)){
                listNew.add(str);
            }
        }
        System.out.println(
 
"listNew = [" + listNew.toString() + "]");
    }

    //遍歷後判斷賦給另一個list集合
    public static void pastLeep2(List<String> list){
        System.out.println("list = [" + list.toString() + "]");
        List<String> listNew=new ArrayList<>();
        for (String str:list) {
            if
 
(!listNew.contains(str)){
                listNew.add(str);
            }
        }
        System.out.println("listNew = [" + listNew.toString() + "]");
    }

    //set去重
    public static void pastLeep3(List<String> list){
        System.out.println("list = [" + list + "]");
        Set set = new
 
 HashSet();
        List<String> listNew=new ArrayList<>();
        set.addAll(list);
        listNew.addAll(set);
        System.out.println("listNew = [" + listNew + "]");
    }

    //set去重（縮減為一行）
    public static void pastLeep4(List<String> list){
        System.out.println("list = [" + list + "]");
        List<String> listNew=new ArrayList<>(new HashSet(list));
        System.out.println("listNew = [" + listNew + "]");
    }

    //去重並按自然順序排序
    public static void pastLeep5(List<String> list){
        System.out.println("list = [" + list + "]");
        List<String> listNew=new ArrayList<>(new TreeSet<String>(list));
        System.out.println("listNew = [" + listNew + "]");
    }

List的五種去重方式