Java HashMap两种简便排序方法解析

Map phone=new HashMap();
    phone.put("Apple",8899);
    phone.put("SAMSUNG",7000);
    phone.put("Meizu",2698);
    phone.put("Xiaomi",1800);
    System.out.println(phone);

Set set=phone.keySet();
    Object[] arr=set.toArray();
    Arrays.sort(arr);
    for(Object key:arr){
      System.out.println(key);
    }

    for(Object key:arr){
      System.out.println(key+": "+phone.get(key));
    }

 List<Map.Entry<String, Integer>> list = new ArrayList<Map.Entry<String, Integer>>(phone.entrySet()); //转换为list

list.sort(new Comparator<Map.Entry<String, Integer>>() {
     @Override
     public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
       return o2.getValue().compareTo(o1.getValue());
     }
   });

Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
      @Override
      public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
        return o2.getValue().compareTo(o1.getValue());
      }
    });

//for循环
     for (int i = 0; i < list.size(); i++) {
      System.out.println(list.get(i).getKey() + ": " + list.get(i).getValue());
    }   
 //for-each循环
      for (Map.Entry<String, Integer> mapping : list){
      System.out.println(mapping.getKey()+": "+mapping.getValue());
    }

//for
    for (int i = 0; i < list.size(); i++) {
      System.out.println(list.get(i).getKey() + ": " +list.get(i).getValue());
    }
    System.out.println();
    //for-each
    for (Map.Entry<String, Integer> mapping : list) {
      System.out.println(mapping.getKey() + ": " +mapping.getValue());
    }