HashMap的两种排序方式

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Map<String, Integer> map = new HashMap<String, Integer>();map.put("d", 2);map.put("c", 1);map.put("b", 1);map.put("a", 3);List<Map.Entry<String, Integer>> infoIds =    new ArrayList<Map.Entry<String, Integer>>(map.entrySet());//排序前for (int i = 0; i < infoIds.size(); i++) {    String id = infoIds.get(i).toString();    System.out.println(id);}//d 2//c 1//b 1//a 3//排序Collections.sort(infoIds, new Comparator<Map.Entry<String, Integer>>() {       public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {              //return (o2.getValue() - o1.getValue());         return (o1.getKey()).toString().compareTo(o2.getKey());    }}); //排序后for (int i = 0; i < infoIds.size(); i++) {    String id = infoIds.get(i).toString();    System.out.println(id);}//根据key排序//a 3//b 1//c 1//d 2//根据value排序//a 3//d 2//b 1//c 1

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