Java：如何在哈希图中获取具有相同值的键集

您可以使用

MultiMap

Map<Integer, String> map = new HashMap<Integer, String>();map.put(1, "x");map.put(2, "y");map.put(2, "z");map.put(3, "x");map.put(4, "y");map.put(5, "z");map.put(6, "x");map.put(7, "y");System.out.println("Original map: " + map);Multimap<String, Integer> multiMap = HashMultimap.create();for (Entry<Integer, String> entry : map.entrySet()) {  multiMap.put(entry.getValue(), entry.getKey());}System.out.println();for (Entry<String, Collection<Integer>> entry : multiMap.asMap().entrySet()) {  System.out.println("Original value: " + entry.getKey() + " was mapped to keys: "      + entry.getValue());}

打印输出：

Original map: {1=x, 2=z, 3=x, 4=y, 5=z, 6=x, 7=y}Original value: z was mapped to keys: [2, 5]Original value: y was mapped to keys: [4, 7]Original value: x was mapped to keys: [1, 3, 6]

每@ noahz 的建议，

forMap

invertFrom

HashMultimap<String, Integer> multiMap =    Multimaps.invertFrom(Multimaps.forMap(map),         HashMultimap.<String, Integer> create());

代替：

Multimap<String, Integer> multiMap = HashMultimap.create();for (Entry<Integer, String> entry : map.entrySet()) {  multiMap.put(entry.getValue(), entry.getKey());}