Java Unbounded Wildcards 🎯

Java provides a powerful feature called Wildcards to handle generic types more flexibly. In this lesson, we'll focus on Unbounded Wildcards.

What are Unbounded Wildcards? 📝

Unbounded wildcards, also known as ?, are used when you want to create a method or a field that can handle any type of object. They are called unbounded because they don't specify the type of the object.

java

List<?> list = new ArrayList<>(); // This list can hold any type of object

Why use Unbounded Wildcards? 💡

Unbounded wildcards are useful when you want to write a method that can handle any subtype of a specific type. This helps in writing more flexible and reusable code.

Example of Unbounded Wildcards 🎯

Let's consider a simple example of a method that accepts a list and returns the maximum element.

java

import java.util.List;

public class UnboundedWildcardsExample {

    public static void main(String[] args) {
        List<Integer> intList = List.of(1, 2, 3, 4, 5);
        List<String> stringList = List.of("A", "B", "C", "D", "E");

        System.out.println("Max Integer: " + getMax(intList));
        System.out.println("Max String: " + getMax(stringList));
    }

    public static <T> T getMax(List<T> list) {
        T max = list.get(0);

        for (T element : list) {
            if (element.compareTo(max) > 0) {
                max = element;
            }
        }

        return max;
    }
}

In this example, we have a method called getMax that accepts a generic list of type T. The list can contain any type of elements, and the method returns the maximum element in the list.

Quiz 🎯

Conclusion 📝

Unbounded wildcards are a powerful feature in Java that allows you to write more flexible and reusable code. They can handle any subtype of a specific type, making them useful in various scenarios.

In the next lesson, we'll explore Bounded Wildcards in more detail. Stay tuned! 🎯