Get generic type of class at runtime

Question

How can I achieve this?

public class GenericClass
{
    public Type getMyType()
    {
        //How do I return the type of T?
    }
}

Answer 1

Use Guava.

import com.google.common.reflect.TypeToken;
import java.lang.reflect.Type;

public abstract class GenericClass {
  private final TypeToken typeToken = new TypeToken(getClass()) { };
  private final Type type = typeToken.getType(); // or getRawType() to return Class

  public Type getType() {
    return type;
  }

  public static void main(String[] args) {
    GenericClass example = new GenericClass() { };
    System.out.println(example.getType()); // => class java.lang.String
  }
}

A while back, I posted some full-fledge examples including abstract classes and subclasses here.

Note: this requires that you instantiate a subclass of GenericClass so it can bind the type parameter correctly. Otherwise it'll just return the type as T.