OnJava8-Examples/generics/RestrictedComparablePets.java

// generics/RestrictedComparablePets.java
// <20>2015 MindView LLC: see Copyright.txt

class Hamster extends ComparablePet
implements Comparable<ComparablePet> {
  public int compareTo(ComparablePet arg) { return 0; }
}

// Or just:

class Gecko extends ComparablePet {
  public int compareTo(ComparablePet arg) { return 0; }
}