// In this version of Stats, the type argument for 
// T must be either Number, or a class derived 
// from Number. 
class Stats<T extends Number> {  
  T[] nums; // array of Number or subclass 
    
  // Pass the constructor a reference to   
  // an array of type Number or subclass. 
  Stats(T[] o) {  
    nums = o;  
  }  
  
  // Return type double in all cases. 
  double average() {  
    double sum = 0.0; 
 
    for(int i=0; i < nums.length; i++)  
      sum += nums[i].doubleValue(); 
 
    return sum / nums.length; 
  }  
}  
  
// Demonstrate Stats.  
class BoundsDemo {  
  public static void main(String args[]) {  
 
    Integer inums[] = { 1, 2, 3, 4, 5 }; 
    Stats<Integer> iob = new Stats<Integer>(inums);   
    double v = iob.average(); 
    System.out.println("iob average is " + v); 
 
    Double dnums[] = { 1.1, 2.2, 3.3, 4.4, 5.5 }; 
    Stats<Double> dob = new Stats<Double>(dnums);   
    double w = dob.average(); 
    System.out.println("dob average is " + w); 
 
    // This won't compile because String is not a 
    // subclass of Number. 
//    String strs[] = { "1", "2", "3", "4", "5" }; 
//    Stats<String> strob = new Stats<String>(strs);   
  
//    double x = strob.average(); 
//    System.out.println("strob average is " + v); 
 
  }  
}