What are best practices for working with wildcards (?)?

When working with wildcards in Java, especially with generics, it's essential to follow some best practices to ensure type safety and maintainability of your code. Wildcards can enhance flexibility but may also introduce complexity. Here are some best practices to consider:

  • Use '? extends T' for Producer Types: This is useful when you want to read items from a structure.
  • Use '? super T' for Consumer Types: This is preferred when you want to write items to a structure.
  • Avoid Raw Types: Using raw types can lead to runtime errors. Always use generics.
  • Limit the Scope of Wildcards: Use wildcards only when necessary and preferable for your use case.
  • Consider Using Bounded Type Parameters: If wildcards become too confusing, consider defining bounds on type parameters instead.

Here’s an example of using wildcards in a generic method:

public static void printList(List extends Number> list) { for (Number number : list) { System.out.println(number); } }

Java wildcards generics best practices type safety

Related Questions

How do I avoid rehashing overhead with std::set in multithreaded code?

How do I find elements with custom comparators with std::set for embedded targets?

How do I erase elements while iterating with std::set for embedded targets?

How do I provide stable iteration order with std::unordered_map for large datasets?

How do I reserve capacity ahead of time with std::unordered_map for large datasets?

How do I erase elements while iterating with std::unordered_map in multithreaded code?

How do I provide stable iteration order with std::map for embedded targets?

How do I provide stable iteration order with std::map in multithreaded code?

How do I avoid rehashing overhead with std::map in performance-sensitive code?

How do I merge two containers efficiently with std::map for embedded targets?