OnJava8-Examples/generics/LostInformation.java

// generics/LostInformation.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
import java.util.*;

class Frob {}
class Fnorkle {}
class Quark<Q> {}
class Particle<POSITION, MOMENTUM> {}

public class LostInformation {
  public static void main(String[] args) {
    List<Frob> list = new ArrayList<>();
    Map<Frob, Fnorkle> map = new HashMap<>();
    Quark<Fnorkle> quark = new Quark<>();
    Particle<Long, Double> p = new Particle<>();
    System.out.println(Arrays.toString(
      list.getClass().getTypeParameters()));
    System.out.println(Arrays.toString(
      map.getClass().getTypeParameters()));
    System.out.println(Arrays.toString(
      quark.getClass().getTypeParameters()));
    System.out.println(Arrays.toString(
      p.getClass().getTypeParameters()));
  }
}
/* Output:
[E]
[K, V]
[Q]
[POSITION, MOMENTUM]
*/