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Practice Questions
Test your understanding with targeted questions related to the topic.
Question 1
Easy
What is a HashMap?
💡 Hint: Think about collections that store pairs.
Question 2
Easy
Can a HashMap have a null key?
💡 Hint: Consider how many null values a HashMap can store.
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 type of collection is a HashMap?
- Ordered
- Unordered
- Sorted
💡 Hint: Think about the nature of HashMap organization.
Question 2
True or False: HashMap allows multiple null keys.
- True
- False
💡 Hint: How many null keys can you have in a HashMap?
Solve 1 more question and get performance evaluation
Challenge Problems
Push your limits with challenges.
Question 1
Write a Java program that creates a HashMap to store employee names and IDs, then prints each employee's details using entrySet() method.
💡 Hint: Remember to import java.util.HashMap first!
Question 2
Compare the performance of a HashMap versus a TreeMap for inserting 1000 elements. What observations can you make?
💡 Hint: Set up a timer to measure insertion times.
Challenge and get performance evaluation