Programming Languages10 lessons20 quiz questions
Java Core
Master Java core concepts for software engineering interviews, covering OOP, collections, streams, concurrency, JVM internals, and common interview patterns.
What You Will Learn
- ✓OOP Fundamentals — Classes, Inheritance, Polymorphism, Interfaces
- ✓Collections Framework — List, Set, Map, Queue, Choosing the Right Collection
- ✓Generics & Type Safety — Wildcards, Bounded Types, Type Erasure
- ✓Exception Handling — Checked vs Unchecked, Custom Exceptions, Best Practices
- ✓Java 8+ Streams & Lambdas — Functional Interfaces, Stream Pipeline, Collectors
- ✓Multithreading & Concurrency — Thread, ExecutorService, Synchronization, CompletableFuture
- ✓JVM Internals & Memory — Heap, Stack, GC, ClassLoader, JIT
- ✓String Handling & Immutability — String Pool, StringBuilder, intern(), Common Pitfalls
- ✓I/O & Serialization — Streams, NIO, Files API, Object Serialization
- ✓Common Interview Patterns — equals/hashCode, Comparable, Immutable Classes, Builder Pattern
Overview
Master Java core concepts for software engineering interviews, covering OOP, collections, streams, concurrency, JVM internals, and common interview patterns.
Java OOP rests on four pillars: encapsulation, inheritance, polymorphism, abstraction.
Key: abstract class provides partial implementation; interface defines a contract. A class can implement multiple interfaces but extend only one class.
Python Implementation
Sample Quiz Questions
1. What is the output of: String a = "hello"; String b = "hello"; System.out.println(a == b);
·Difficulty: /5
2. Which collection provides O(1) average-case time for get(), put(), and containsKey()?
·Difficulty: /5
3. What happens when you call stream() operations without a terminal operation?
·Difficulty: /5
+ 17 more questions available in the full app.
Related Topics
Master Java Core for Your Next Interview
Get access to full lessons, adaptive quizzes, cheat sheets, code playground, and progress tracking — completely free.