Generic data types

Old style
public abstract class Generic {
 
  public abstract void print(Object o);
 
  class ImplInteger extends Generic {
    public void print(Object o) {
      /* I don't want a cast here, I want generic type usage*/
      Integer n = (Integer)o;
      System.out.println("The integer value is " + n);
    }
  }
  
  class ImplDouble extends Generic {
    public void print(Object o) {
      /* I don't want a cast here, I want generic type usage*/
      Double d = (Double)o;
      System.out.println("The double value is " + d);
    }
  }
}

JDK 1.5 - solution 1
public abstract class Generic<T> {

  public abstract void print(T o);

  class ImplInteger<T extends Integer> extends Generic<T> {
    public void print(T o) {
    System.out.println("The integer value is " + o.intValue());
    }
  }

  class ImplDouble <T extends Double> extends Generic<T> {
    public void print(T o) {
      System.out.println("The double value is " + o.doubleValue());
    }
  }
}

JDK 1.5 - solution 2
public abstract class Generic<T> {

  public abstract void print(T o);

  class ImplInteger extends Generic<Integer> {
    public void print(Integer o) {
      System.out.println("The integer value is " + o.intValue());
    }
  }

  class ImplDouble extends Generic<Double> {
    public void print(Double o) {
      System.out.println("The double value is " + o.doubleValue());
    }
  }
}