Junior Java Developer Interview Questions

3,828 junior java developer interview questions shared by candidates

Core Java & OOPs: Explain OOPs concepts with real-world examples. Difference between String, StringBuilder, and StringBuffer. How Garbage Collection works in Java. Why String is immutable in Java. HashMap vs LinkedHashMap vs TreeMap. HashMap vs ConcurrentHashMap & internal working. Spring Boot & Hibernate: Spring Boot Auto-Configuration explained. Difference between @Component, @Service, and @Repository. Pagination & Sorting in Spring Data JPA. EAGER vs LAZY fetching in Hibernate. Global Exception Handling in Spring Boot. Database & SQL: SQL query to fetch the second-highest salary. How to find duplicate records in a table. INNER JOIN vs LEFT JOIN. DevOps & Others: Docker usage in deployments. REST vs SOAP APIs. Strategies to improve application performance in Java. 💡 Additionally, there was a project-related discussion around my academic work.

Junior Java Developer

Interviewed at Camelq Software Solutions

1
Aug 20, 2025

Core Java & OOPs: Explain OOPs concepts with real-world examples. Difference between String, StringBuilder, and StringBuffer. How Garbage Collection works in Java. Why String is immutable in Java. HashMap vs LinkedHashMap vs TreeMap. HashMap vs ConcurrentHashMap & internal working. Spring Boot & Hibernate: Spring Boot Auto-Configuration explained. Difference between @Component, @Service, and @Repository. Pagination & Sorting in Spring Data JPA. EAGER vs LAZY fetching in Hibernate. Global Exception Handling in Spring Boot. Database & SQL: SQL query to fetch the second-highest salary. How to find duplicate records in a table. INNER JOIN vs LEFT JOIN. DevOps & Others: Docker usage in deployments. REST vs SOAP APIs. Strategies to improve application performance in Java. 💡 Additionally, there was a project-related discussion around my academic work.

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