java Map 按value值排序和按key值排序

向右看齐 2022-08-04 15:46 240阅读 0赞

public class Test {
    
        public static void main(String[] args) throws ClassNotFoundException {
            // TODO Auto-generated method stub
            Map<String, Integer> map = new HashMap<String, Integer>();
            map.put("d", 2);
            map.put("c", 1);
            map.put("b", 4);
            map.put("a", 3);
            map.put("e", 5);
    
            List<Map.Entry<String, Integer>> list =
                new ArrayList<Map.Entry<String, Integer>>(map.entrySet());
            for (int i = 0; i < list.size(); i++) {
                String id = list.get(i).toString();
                System.out.println(id);
            }
            System.out.println("-------------按value排序----------------------------");
            Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {   
                public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {      
                    return (o1.getValue() - o2.getValue()); 
                }
            }); 
            for (int i = 0; i < list.size(); i++) {
                String id = list.get(i).toString();
                System.out.println(id);
            }
            System.out.println("--------------按key排序-----------------------------");
    
            Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {   
                public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {      
                    return (o1.getKey()).toString().compareTo(o2.getKey());
                }
            });
            for (int i = 0; i < list.size(); i++) {
                String id = list.get(i).toString();
                System.out.println(id);
            }
        }
    }
    result：
    d=2
    e=5
    b=4
    c=1
    a=3
    -------------按value排序----------------------------
    c=1
    d=2
    a=3
    b=4
    e=5
    --------------按key排序-----------------------------
    a=3
    b=4
    c=1
    d=2
    e=5