// Fig. 18.15: WildcardTest.java
// Wildcard test program.
import java.util.ArrayList;

public class WildcardTest 
{
   public static void main( String args[] ) 
   {
      // create, initialize and output ArrayList of Integers, then 
      // display total of the elements 
      Integer[] integers = { 1, 2, 3, 4, 5 };
      ArrayList< Integer > integerList = new ArrayList< Integer >();

      // insert elements in integerList
      for ( Integer element : integers )
         integerList.add( element );

      System.out.printf( "integerList contains: %s\n", integerList );
      System.out.printf( "Total of the elements in integerList: %.0f\n\n",
         sum( integerList ) );

      // create, initialize and output ArrayList of Doubles, then 
      // display total of the elements 
      Double[] doubles = { 1.1, 3.3, 5.5 };
      ArrayList< Double > doubleList = new ArrayList< Double >();

      // insert elements in doubleList
      for ( Double element : doubles )
         doubleList.add( element );

      System.out.printf( "doubleList contains: %s\n", doubleList );
      System.out.printf( "Total of the elements in doubleList: %.1f\n\n", 
         sum( doubleList ) );

      // create, initialize and output ArrayList of Numbers containing 
      // both Integers and Doubles, then display total of the elements 
      Number[] numbers = { 1, 2.4, 3, 4.1 }; // Integers and Doubles
      ArrayList< Number > numberList = new ArrayList< Number >();

      // insert elements in numberList
      for ( Number element : numbers )
         numberList.add( element );

      System.out.printf( "numberList contains: %s\n", numberList );
      System.out.printf( "Total of the elements in numberList: %.1f\n", 
         sum( numberList ) );
   } // end main

   // calculate total of stack elements
   public static double sum( ArrayList< ? extends Number > list )
   {
      double total = 0; // initialize total

      // calculate sum
      for ( Number element : list )
         total += element.doubleValue();

      return total;
   } // end method sum
} // end class WildcardTest

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