java List 排序

Collections的方式

1，升序排列（默认从小到大）

 public static void main(String[] args) {
        List<Map<String, String>> list = new ArrayList<Map<String, String>>();

        (getData(0));
        (getData(7));
        (getData(5));
        (getData(6));
        (getData(2));

        ("排序前" + list);

        (list, new Comparator<Map<String, String>>() {
            public int compare(Map<String, String> o1, Map<String, String> o2) {
                String str1 = ("countScore").toString();
                String str2 = ("countScore").toString();
                //str1在前，str2在后，默认升序，这里Integer类型的也可以
                return (str2);
            
            }
        });
        ("排序后" + list);
    }

 private static Map<String, String> getData(int num) {
        Map<String, String> map = new HashMap<String, String>();
        ("countScore", (num));
        return map;
    }

2,降序排列

  public static void main(String[] args) {
        List<Map<String, String>> list = new ArrayList<Map<String, String>>();

        (getData(0));
        (getData(7));
        (getData(5));
        (getData(6));
        (getData(2));

        ("排序前" + list);

        (list, new Comparator<Map<String, String>>() {
            public int compare(Map<String, String> o1, Map<String, String> o2) {
                String str1 = ("countScore").toString();
                String str2 = ("countScore").toString();
                //str2在前，str1在后，默认降序
                return (str1);
            }
        });
        ("排序后" + list);
    }

    private static Map<String, String> getData(int num) {
        Map<String, String> map = new HashMap<String, String>();
        ("countScore", (num));
        return map;
    }

foreach的方式

   (ele->{
         ((k, v) -> {
         if((k,"name") && (v,"1号")){
                    int size = ();
                    (size,ele);
                }
                if((k,"name") && (v,"2号")){
                    int size = ();
                    (size,ele);
            }
          });
      });

嵌套for的方式

  for (Map<String, Object> map : list) {
          for (<String, Object> m : ()) {
              ("key:"+() + "    ");
              ("value:"+());
          }
      }