Explain the concept of a wrapper class and its purpose in object-oriented programming.

A wrapper class in object-oriented programming is a class that "wraps" another object or primitive data type, providing additional functionality or an interface. The main purposes of a wrapper class:

• Encapsulating primitive types into objects (for example, in Java, there are wrapper classes for primitives: Integer, Double, etc.).
• Adding extra logic when accessing data or methods.
• Ensuring compatibility with APIs that require objects instead of primitives.
• Managing the lifecycle or state of the wrapped object.

Example: a wrapper class for a string that adds a method to count words.

public class StringWrapper {
    private String str;

    public StringWrapper(String str) {
        this.str = str;
    }

    public int wordCount() {
        if (str == null || str.isEmpty()) return 0;
        return str.trim().split("\\s+").length;
    }

    public String get() {
        return str;
    }
}

Thus, a wrapper class extends the functionality or adapts the behavior of the original object.