Catching ClassCastException in a generic method when doing generic cast

Question

Suppose I have a method

@SuppressWarnings(\"unchecked\")
public  T getNumber() {
   try {
      return (T)number; 
   } catch (ClassC         


        

Answer 1

After type erasure, return (T)number becomes return (Number)number (since Number is the type bound of T), which doesn't throw an exception (since number is an instance of Integer).

On the other hand, the assignment

Float f = getNumber();

is compiled to

Float f = (Float) getNumber();

since getNumber() returns a Number, which can't be assigned to a Float variable without a cast.

This cast throws the ClassCastException when getNumber() is not a Float.

4.6. Type Erasure

Type erasure is a mapping from types (possibly including parameterized types and type variables) to types (that are never parameterized types or type variables). We write |T| for the erasure of type T. The erasure mapping is defined as follows...

The erasure of a type variable (§4.4) is the erasure of its leftmost bound.