对HashMap中的值进行排序

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", 98.5);
map.put("B", 85.0);
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);
}

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
}