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Practice Questions
Test your understanding with targeted questions related to the topic.
Question 1
Easy
What is the syntax for an upper bound wildcard?
💡 Hint: Look for the keyword 'extends'.
Question 2
Easy
What kind of types can be used with a lower bound wildcard?
💡 Hint: Think of what superclass means.
Practice 4 more questions and get performance evaluation
Interactive Quizzes
Engage in quick quizzes to reinforce what you've learned and check your comprehension.
Question 1
What does List<? extends Number> allow?
- Only Numbers
- Any subclass of Number
- Only Integer
💡 Hint: Think about the subclasses!
Question 2
Can you add elements to a List defined as List<? extends Number>?
- True
- False
💡 Hint: Consider how wildcards restrict adding elements.
Solve 1 more question and get performance evaluation
Challenge Problems
Push your limits with challenges.
Question 1
Design a generic method that can accept a list of pets which are subclasses of a superclass, and also allow adding mammals to a list of animals.
💡 Hint: Consider what types you want to allow and what you need to insert.
Question 2
How would you refactor a method that uses non-bounded types into one that effectively uses bounded wildcards?
💡 Hint: Identify where you need to read and write in your current implementation.
Challenge and get performance evaluation