Mega Code Archive
Wildcard test program
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import java.util.ArrayList;
public class MainClass {
public static void main(String args[]) {
Integer[] integers = { 1, 2, 3, 4, 5 };
ArrayList<Integer> integerList = new ArrayList<Integer>();
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));
Double[] doubles = { 1.1, 3.3, 5.5 };
ArrayList<Double> doubleList = new ArrayList<Double>();
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));
Number[] numbers = { 1, 2.4, 3, 4.1 }; // Integers and Doubles
ArrayList<Number> numberList = new ArrayList<Number>();
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));
}
public static double sum(ArrayList<? extends Number> list) {
double total = 0;
for (Number element : list)
total += element.doubleValue();
return total;
}
}
integerList contains: [1, 2, 3, 4, 5]
Total of the elements in integerList: 15
doubleList contains: [1.1, 3.3, 5.5]
Total of the elements in doubleList: 9.9
numberList contains: [1, 2.4, 3, 4.1]
Total of the elements in numberList: 10.5
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