Getting Started: Java Interview Questions

Junior Java developer interviews heavily prioritize foundational language mechanics and object-oriented principles, and stumbling on these basics is a fast way to fail a technical screen. This course is a direct, comprehensive breakdown of the core concepts you need to master to confidently answer technical questions in a Java interview. You will start with the building blocks, covering primitives, variables, operators, and strings, as well as type conversion and casting. From there, you will move into control flow and method design, exploring conditionals, loops, parameters, and method overloading. Next, we examine object-oriented programming from the ground up. You will learn how to articulate the differences between abstract classes and interfaces, and how to accurately explain encapsulation, access modifiers, inheritance, and polymorphism. We will also cover exactly how Java handles memory and equality, detailing the crucial differences between primitives and references, pass-by-value semantics, wrapper classes, autoboxing, and the strict contract between the equals and hashCode methods.

There is a heavy focus on the Collections Framework, where you will compare arrays against List implementations like ArrayList and LinkedList, and understand exactly when to use a HashMap, TreeMap, Set, Queue, or Deque. This leads directly into generics, where we clarify type parameters, bounded types, and wildcards. The course then brings your knowledge up to date with functional programming, walking through lambdas, functional interfaces, and the Stream pipeline, including intermediate operations, terminal operations, and collectors. You will also review exception handling by contrasting checked and unchecked exceptions, using throw and throws, managing resources with try-with-resources, and writing custom exceptions. Finally, we explore modern language additions like records, sealed types, pattern matching, var, switch expressions, and text blocks, before wrapping up with the platform itself. You will finish the course able to explain the differences between the JVM, JRE, and JDK, how bytecode works, and the basics of the Java memory model, classpath, packages, modules, and garbage collection.