How are extensions used in Java?

In Java, there are no native "extensions" like in Kotlin that allow adding methods to existing classes without inheritance or using wrapper patterns.

In Java, other approaches are used to achieve similar goals:

• Inheritance: Creating a subclass that inherits the functionality of the parent class and adds new methods.
• Decorator: Wrapping an existing object in another object that adds new functionality while maintaining the same interface.
• Static utility classes: Grouping related static methods that operate on objects of other classes.

Example of a static utility class:

class StringUtils {
    // Static method that adds functionality to String
    public static boolean isNullOrEmpty(String str) {
        return str == null || str.isEmpty();
    }
}