guava之Multimap

键可重复的map

Multimap<Integer,String> mp = HashMultimap.create();
mp.put(1,"a");
mp.put(1,"b");
mp.put(1,"c");
mp.put(1,"c");
mp.put(2,"d");

Collection<String> c = mp.get(1);
System.out.println(c.toString());
System.out.println(mp.size());

结果:

[a, b, c]
4