TreeMap按照value进行排序

public class Testing {  

  

    public static void main(String[] args) {  

  

        HashMap<String,Double> map = new HashMap<String,Double>();  

        ValueComparator bvc =  new ValueComparator(map);  

        TreeMap<String,Double> sorted_map = new TreeMap<String,Double>(bvc);  

  

        map.put("A",99.5);  

        map.put("B",67.4);  

        map.put("C",67.4);  

        map.put("D",67.3);  

  

        System.out.println("unsorted map: "+map);  

  

        sorted_map.putAll(map);  

  

        System.out.println("results: "+sorted_map);  

    }  

}  

  

class ValueComparator implements Comparator<String> {  

  

    Map<String, Double> base;  

    public ValueComparator(Map<String, Double> base) {  

        this.base = base;  

    }  

  

    // Note: this comparator imposes orderings that are inconsistent with equals.      

    public int compare(String a, String b) {  

        if (base.get(a) >= base.get(b)) {  

            return -1;  

        } else {  

            return 1;  

        } // returning 0 would merge keys  

    }  

}