Question

How to call a Custom Generic method by reflection in java?

class Person
{
  public <T> void print(T t)
   {
      System.out.println(t.toString());
   }
}

Answer 1

Generics are erased at compile time, they only provide extra information to the compiler to determine errors. They do not actually change the signature of the method in the .class file.

This means that you call a generic method by reflection in Java exactly the same way as you would call a non-generic method in Java, except that instead of specifying a type of T, you would specify a type of Object.

There are so many tutorials on how to call a regular method by reflection that I hesitate to add yet another; however, if you really need direction on how to call a method by reflection, please add a comment below and I’ll add the necessary code.

If you find that things are not working as expected, you can always run javap on the compiled class file to verify that you are using the right objects in the argument list. It might be possible that if you specify a <T extends List> type generic signature, the resulting parameter object might actually be a List object.