java - 检查Java中持有对象的引用的类名

Question

class A {
}

class B extends A {
}

class TestType {
   public static void main(String args[]) {
      A a = new B();
      // I wish to use reference 'a' to check the Reference-Type which is 'A'.
   }
}

有可能吗？如果不是，请说明原因。

Answer 1

Chris Jester-Young's comment很棒。它说:

You can't. The static type of local variables is not retained in the bytecode, nor at runtime. (If it's a field, you can use reflection on the field's containing class to get the field's type.)

另见 What is the concept of erasure in generics in Java?

和http://gafter.blogspot.com/search?q=super+type+token .