Map按照Value排序（升序，降序）---（Comparator）

在开发的时候，写一个搜索逻辑，用到好多排序，因为用到了map，数据都放在了map中，这时候需要排序才能用，就有了，这个排序：Map按照Value排序（升序，降序）

public class mapValueCompareSort {    
          public static void main(String[] args) { 
 //value降序排 HashMap<String,Double> mapDesc = new HashMap<String,Double>(); ValueComparatorDesc bvcDESC = new ValueComparatorDesc(mapDesc); TreeMap<String,Double> sorted_map_Desc = new TreeMap<String,Double>(bvcDESC); mapDesc.put("A",99.5); mapDesc.put("B",67.4); mapDesc.put("C",67.4); mapDesc.put("D",67.3); mapDesc.put("E",11.0); mapDesc.put("F",-0.1); mapDesc.put("G",0.1); mapDesc.put("H",-99.1); System.out.println("降序=====unsorted map: "+mapDesc); sorted_map_Desc.putAll(mapDesc); System.out.println("降序=====results: "+sorted_map_Desc); //Value升序排 HashMap<String,Double> mapAsc = new HashMap<String,Double>(); ValueComparatorAsc bvcAsc = new ValueComparatorAsc(mapAsc); TreeMap<String,Double> sorted_mapAsc = new TreeMap<String,Double>(bvcAsc); mapAsc.put("A",99.5); mapAsc.put("B",67.4); mapAsc.put("C",67.4); mapAsc.put("D",67.3); mapAsc.put("E",11.0); mapAsc.put("F",-0.1); mapAsc.put("G",0.1); mapAsc.put("H",-99.1); System.out.println("升序====unsorted map: "+mapAsc); sorted_mapAsc.putAll(mapAsc); System.out.println("升序====results: "+sorted_mapAsc); } } class ValueComparatorDesc implements Comparator<String> { Map<String, Double> base; public ValueComparatorDesc(Map<String, Double> base) { this.base = base; } public int compare(String a, String b) { if (base.get(a) >= base.get(b)) { return -1; } else { return 1; } } }class ValueComparatorAsc implements Comparator<String> { Map<String, Double> base; public ValueComparatorAsc(Map<String, Double> base) { this.base = base; } public int compare(String a, String b) { if (base.get(a) <= base.get(b)) { return -1; } else { return 1; } } }

输出结果是：
降序=====unsorted map: {D=67.3, E=11.0, F=-0.1, G=0.1, A=99.5, B=67.4, C=67.4, H=-99.1}
降序=====results: {A=99.5, C=67.4, B=67.4, D=67.3, E=11.0, G=0.1, F=-0.1, H=-99.1}
升序====unsorted map: {D=67.3, E=11.0, F=-0.1, G=0.1, A=99.5, B=67.4, C=67.4, H=-99.1}
升序====results: {H=-99.1, F=-0.1, G=0.1, E=11.0, D=67.3, C=67.4, B=67.4, A=99.5}

这个排序的时候，值可以double的，
上篇文章Map按照Value排序（升序，降序）--string，这个由于Collections.sort只支持String，String的类型 ，给value排序的时候就只能整数的排序，因为不满足我的需求，就重新写了一个，整理一下，以后可以用到的时候，直接用