[Java] Map - Value 값으로 정렬

Map<String, Integer> map = new HashMap<>();
map.put("math", 100);
map.put("english", 80);
map.put("history", 90);

List<String> keySetList = new ArrayList<>(map.keySet());
System.out.println("before");
for (String key : keySetList) {
    System.out.println(key + ": " + map.get(key));
}

Collections.sort(keySetList, (o1, o2) -> map.get(o1).compareTo(map.get(o2)));
System.out.println("after");
for (String key : keySetList) {
    System.out.println(key + ": " + map.get(key));
}

 

 

<결과>

before
english: 80
math: 100
history: 90
after
english: 80
history: 90
math: 100