Constraining Type Variables

• Type variables can be constrained with bounds

  public static <E extends Comparable> E min(E[] a)
  {
     E smallest = a[0];
     for (int i = 1; i < a.length; i++)
        if (a[i].compareTo(smallest) < 0) smallest = a[i];
     return smallest;
  }

• Can call min with a String[] array but not with a Rectangle[] array
• Comparable bound necessary for calling compareTo
  Otherwise, min method would not have compiled