JavaProgrammingHacktoberFest/Generics/WildcardExample.java at main · basukinath/JavaProgrammingHacktoberFest · GitHub

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package Generics;

import java.util.Arrays;

import java.util.List;

public class WildcardExample {

// Upper-bounded wildcard: accepts a list of Number or its subclasses

public static double sumOfList(List<? extends Number> list) {

double sum = 0.0;

for (Number n : list) {

sum += n.doubleValue();

}

return sum;

}

// Unbounded wildcard: accepts a list of any type

public static void printList(List<?> list) {

for (Object elem : list) {

System.out.print(elem + " ");

}

System.out.println();

}

// Lower-bounded wildcard: accepts a list of Integer or its superclasses

public static void addIntegers(List<? super Integer> list) {

list.add(10);

list.add(20);

}

public static void main(String[] args) {

List<Integer> intList = Arrays.asList(1, 2, 3);

System.out.println("Sum of integers: " + sumOfList(intList));

List<Double> doubleList = Arrays.asList(1.1, 2.2, 3.3);

System.out.println("Sum of doubles: " + sumOfList(doubleList));

System.out.print("Integer list: ");

printList(intList);

System.out.print("Double list: ");

printList(doubleList);

List<Number> numList = Arrays.asList(1, 2.5, 3L);

addIntegers(numList);

System.out.println("List after adding integers: " + numList);

}

JavaProgrammingHacktoberFest/Generics/WildcardExample.java at main · basukinath/JavaProgrammingHacktoberFest · GitHub

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