A brief discussion of Java's Map sort by value (Map sort by value)

Map map = new TreeMap();
map.put("me", 1000);
map.put("and", 4000);
map.put("you", 3000);
map.put("food", 10000);
map.put("hungry", 5000);
map.put("later", 6000);

key value
me 1000
you 3000
and 4000
hungry 5000
later 6000
food 10000

import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;
 
public class Main {
  public static void main(String[] args) {
 
    Set set = new TreeSet();
    set.add(new Pair("me", "1000"));
 
    set.add(new Pair("and", "4000"));
    set.add(new Pair("you", "3000"));
 
    set.add(new Pair("food", "10000"));
    set.add(new Pair("hungry", "5000"));
 
    set.add(new Pair("later", "6000"));
    set.add(new Pair("myself", "1000"));
 
    for (Iterator i = set.iterator(); i.hasNext();)
 
      System.out.println(i.next());
  }
}
 
class Pair implements Comparable {
  private final String name;
  private final int number;
 
  public Pair(String name, int number) {
    this.name = name;
    this.number = number;
  }
 
  public Pair(String name, String number) throws NumberFormatException {
    this.name = name;
    this.number = Integer.parseInt(number);
 
  }
 
  public int compareTo(Object o) {
    if (o instanceof Pair) {
      int cmp = Double.compare(number, ((Pair) o).number);
      if (cmp != 0) {
        return cmp;
      }
      return name.compareTo(((Pair) o).name);
    }
 
    throw new ClassCastException("Cannot compare Pair with "
        + o.getClass().getName());
 
  }
 
  public String toString() {
    return name + ' ' + number;
  }
}

typedef pair<string, int> PAIR;
 
int cmp(const PAIR& x, const PAIR& y)
{
  return x.second > y.second;
}
 
map<string,int> m;
vector<PAIR> vec;
for (map<wstring,int>::iterator curr = m.begin(); curr != m.end(); ++curr)
{
  vec.push_back(make_pair(curr->first, curr->second));
}
sort(vec.begin(), vec.end(), cmp);

public static Map sortByValue(Map map) {
    List list = new LinkedList(map.entrySet());
    Collections.sort(list, new Comparator() {
 
      public int compare(Object o1, Object o2) {
        return ((Comparable) ((Map.Entry) (o1)).getValue())
            .compareTo(((Map.Entry) (o2)).getValue());
 
      }
    });
    Map result = new LinkedHashMap();
 
    for (Iterator it = list.iterator(); it.hasNext();) {
      Map.Entry entry = (Map.Entry) it.next();
      result.put(entry.getKey(), entry.getValue());
    }
    return result;
  }
 
  public static Map sortByValue(Map map, final boolean reverse) {
    List list = new LinkedList(map.entrySet());
    Collections.sort(list, new Comparator() {
 
      public int compare(Object o1, Object o2) {
        if (reverse) {
          return -((Comparable) ((Map.Entry) (o1)).getValue())
              .compareTo(((Map.Entry) (o2)).getValue());
        }
        return ((Comparable) ((Map.Entry) (o1)).getValue())
            .compareTo(((Map.Entry) (o2)).getValue());
      }
    });
 
    Map result = new LinkedHashMap();
    for (Iterator it = list.iterator(); it.hasNext();) {
      Map.Entry entry = (Map.Entry) it.next();
      result.put(entry.getKey(), entry.getValue());
    }
    return result;
  }
 
 
 
 
        Map map = new HashMap();
    map.put("a", 4);
    map.put("b", 1);
    map.put("c", 3);
    map.put("d", 2);
    Map sorted = sortByValue(map);
    System.out.println(sorted);
// output : {b=1, d=2, c=3, a=4}
 
或者还可以这样：
Map map = new HashMap();
    map.put("a", 4);
    map.put("b", 1);
    map.put("c", 3);
    map.put("d", 2);
 
    Set<Map.Entry<String, Integer>> treeSet = new TreeSet<Map.Entry<String, Integer>>(
        new Comparator<Map.Entry<String, Integer>>() {
          public int compare(Map.Entry<String, Integer> o1,
              Map.Entry<String, Integer> o2) {
            Integer d1 = o1.getValue();
            Integer d2 = o2.getValue();
            int r = d2.compareTo(d1);
 
            if (r != 0)
              return r;
            else
              return o2.getKey().compareTo(o1.getKey());
          }
 
        });
    treeSet.addAll(map.entrySet());
    System.out.println(treeSet);
    // output : [a=4, c=3, d=2, b=1]

def result = map.sort(){ a, b ->
      b.value.compareTo(a.value)
    }

h = {"a":2,"b":1,"c":3}
i = h.items() // i = [('a', 2), ('c', 3), ('b', 1)]
i.sort(lambda (k1,v1),(k2,v2): cmp(v2,v1) ) // i = [('c', 3), ('a', 2), ('b', 1)]