Java interview questions for 3 years experience

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Exception Handling: Explain checked vs unchecked exceptions. When to use try/catch blocks vs throwing and handling exceptions.
Multithreading: How to create threads in Java? Explain thread lifecycle. Know difference between sleep() and wait() methods.
Collections Framework: Difference between List, Set and Map interfaces. Know common methods like contains(), iterator() etc.
Generics: Explain generics in Java. Know difference between raw types and parameterized types.
JDBC and Database: Steps for establishing a JDBC connection. Using PreparedStatements vs Statements.
Java 8 Features: Lambdas, method reference, streams, functional interfaces. When to use which new feature.
Spring Framework: What is dependency injection? Know Spring MVC request flow. Explain how Spring beans are configured.
Design Patterns: Experience with common patterns like singleton, factory, builder, observer, strategy etc.
Testing: Unit testing frameworks like JUnit and Mockito. How to test private, void or dependent methods.
Build Tools: Experience with tools like Maven, Git, Jenkins. Understanding of building and deploying Java applications.