Which of the following is not a wildcard type in Java generics?Select one:a. ?b. +c. *d. -

Breakdown the Problem

1. Identify the different wildcard types in Java generics.
2. Analyze the options given in the question to determine which one is not a wildcard type.

Relevant Concepts

• In Java generics, wildcards are used to represent an unknown type. The common types of wildcards include:
  • ?: Represents an unknown type (unbounded wildcard).
  • ? extends T: Represents a type that is a subtype of T (upper-bounded wildcard).
  • ? super T: Represents a type that is a supertype of T (lower-bounded wildcard).

Analysis and Detail

1. Looking at the options provided:
   • a. ?: This is a valid wildcard representing an unknown type.
   • b. +: This is not a valid wildcard type in Java generics.
   • **c. ***: This is also not a valid wildcard in Java generics.
   • d. -: Similar to +, this is also not a valid wildcard.

Verify and Summarize

After analyzing the concept of wildcards in Java generics, it's clear that while ? is a valid wildcard type representing an unknown type, the rest of the options represent symbols not utilized as wildcards in Java.

Final Answer

Option b. + is not a wildcard type in Java generics.