In Java generics, what does the '?' symbol represent?Question 2Answera.Any typeb.Object typec.Generic typed.Wildcard type

Understanding the '?' Symbol in Java Generics

In Java generics, the '?' symbol represents an important concept known as a "wildcard." Wildcards are used when you want to express that a method or a class can accept or work with a variety of types, without being specific about which type it is.

1. Types of Wildcards: There are three types of wildcards in Java:

   • Unbounded Wildcard: Represented by ?, it can stand for any type, allowing for flexibility in method parameters.
   • Upper Bounded Wildcard: Written as ? extends Type, it restricts the unknown type to be a subtype of a specific class or interface.
   • Lower Bounded Wildcard: Denoted as ? super Type, it specifies that the unknown type must be a supertype of a specific class.

2. Use Cases: Wildcards are particularly useful in situations where you want to write a method that can be applied to a number of different types. For example, if you have a method that operates on List<?>, it can accept a list of any type, such as List<Integer>, List<String>, etc.

Final Answer

Based on the provided options, the correct choice is:

• d. Wildcard type