Map key为Integer类型时用Long值取value问题

Map<Integer, String> map1 = new ConcurrentHashMap<Integer, String>();
			map1.put(11, "11");
			map1.put(22, "22");
			long key1 = 11;
			System.out.println(map1.get(key1));  // null
			
			Map<Long, String> map2 = new ConcurrentHashMap<Long, String>();
			map2.put(11L, "11");
			map2.put(22L, "22");
			int key2 = 11;
			System.out.println(map1.get(key2));  // 11

总结： Map的key为Integer时，用Long型值无法取到value；Map的key为Long时，用Integer值可以取到value。