FAQs for Top 50 Core Java Interview Questions and Answers in 2023

Q1. What are the most important features of Java?

A. The most important features of Java include its simplicity, platform independence, object-oriented programming, secure, multithreading, and robustness.

Q2. What is the difference between an abstract class and an interface in Java?

A. An abstract class is a class that cannot be instantiated and can contain both abstract and non-abstract methods. An interface, on the other hand, is a contract that defines a set of methods that a class must implement.

Q3. What is the purpose of the JVM in Java?

A. The purpose of the JVM (Java Virtual Machine) in Java is to provide the runtime environment for Java bytecode to run.

Q4. What is the difference between a constructor and a method in Java?

A. A constructor is a special method that is used to initialize objects, while a method is a set of instructions that can be called on an object to perform a specific task.

Q5. What is the difference between a checked and an unchecked exception in Java?

A. Checked exceptions are checked at compile time and must be handled in the program or declared in the method signature. Unchecked exceptions, on the other hand, are not checked at compile time and do not need to be handled or declared. Examples of checked exceptions include IOException and ClassNotFoundException, while examples of unchecked exceptions include NullPointerException and ArrayIndexOutOfBoundsException.