100+ Core Java Tricky Interview Questions and Answers

This video aims to cover Java interview questions and answers in a structured manner. The speaker explains the differences between JVM, JRE, and JDK, describing JVM as the engine that runs Java bytecode, making Java platform-independent, JRE as containing JVM and libraries necessary to run Java programs, and JDK as a development kit for developers. JVM's architecture consists of a class loader, runtime data areas, and an execution engine. The discussion includes the necessity of JRE for running Java applications and tools for bundling applications with their own JRE version.

The discussion on JVM continues, explaining its memory storage such as heap space, stack memory, and method area. The speaker introduces an interview preparation kit, including enterprise projects like a credit score analysis tool in Sweden and a claims processing system in the USA. This kit provides structured and organized Java Spring Boot interview materials and supports resume building. A high chance of confidence-building for interviewees is assured.

Explanation of garbage collection in Java, detailing algorithms like Mark-Sweep and conditions like memory leaks. Discusses Java's partial object-oriented nature due to primitive data types and the advantages of such a design. It explains the concept of object-oriented programming aiding in organizing and updating code and addresses the significance of public static void main as the program entry point. Further, details about method overloading and JVM's response to overloaded methods are described.

It covers the contrast between primitive and non-primitive data types, noting that primitives have fixed sizes and are not objects, while non-primitives are classes defined by programmers. Discussions revolve around nullability, the non-existence of pointers to enhance security, use of wrapper classes for autoboxing/unboxing, and the workings of Object-oriented principles in Java. The section ends with access control in Java classes and methods.

Shift in focus to encapsulation and its importance in securing and controlling data access within Java programs. Abstraction in Java is introduced as a method to simplify complex systems by hiding unnecessary details, allowing programmers to manipulate interface methods without understanding their workings internally. An explanation of interfaces and the differences from abstract classes in Java is provided.

Explains the use of inheritance and composition, distinction between the two, and concepts like polymorphism in Java. Discusses dynamic method dispatch and the unavailability of polymorphic constructors. Different aspects of method abstraction, interface vs abstract class usage, and the implementation of multiple inheritances via interfaces are outlined. Encapsulation is linked to security and data integrity.