Assignment - WildcardTest

Assignment - WildcardTest

//wildcardTest.java

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 interger list

        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

//total the elements; using a wildcard in the ArrayList parameter

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