Java Map Generic

Question

顶部地图有3个子地图，每个子地图有不同的对象。

如下面的代码，如何将通用添加到地图顶部？

    Map<String,Map> top = new ConcurrentHashMap<String, Map>();

    Map<String,TypeA> subA = new ConcurrentHashMap<String,TypeA>();
    Map<Long,TypeB> subB = new ConcurrentHashMap<String,TypeB>();
    Map<String, long[]> sbuC = new ConcurrentHashMap<String,TypeC>();
    top.put("SUB_A", subA);
    top.put("SUB_B", subB);
    top.put("SUB_C", subC);

Answer 1

试试这个：

Map<String,Map<<? extends  Object,?>> top = new ConcurrentHashMap<String, Map< <? extends Object,?>>();

键是object，值是任何类型。