Java – Index

Welcome to the complete Java resource centre. Start with the revision guide to rebuild the full picture quickly, then grind the question tracks below.

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Revision Guide

Rapid, interview-focused revision of everything you need — from JVM internals to concurrency.

• Part 1: JVM Memory, Types & Fundamentals JVM memory model, primitives vs objects, operators, and control flow in one sitting.
• Part 2: OOP & Core Classes Classes, interfaces, inheritance, equals-hashCode, and the String family.
• Part 3: Collections & Generics List, Set, Map internals, iterators, and how generics behave at runtime.
• Part 4: Streams, Lambdas & Functional Java Functional interfaces, streams pipeline, method references, and Optional.
• Part 5: Exceptions, Concurrency & JVM Exception hierarchy, try-with-resources, threads, locks, and garbage collection.

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Top 10 Questions

The most frequently asked Java placement questions.

• Top 10 Java Questions - Part 1 The first 10 questions interviewers ask the most.

Top 25 Questions

Core patterns and concepts for placement preparation.

• Top 25 - Part 1 Essential core Java concepts for placement preparation.
• Top 25 - Part 2 Intermediate concepts and common interview patterns.

Top 50 Questions

Comprehensive practice across the full Java syllabus.

• Top 50 - Part 1 First 15 of the most frequently asked Java questions.
• Top 50 - Part 2 Middle 15 of the top 50 Java placement questions.
• Top 50 - Part 3 Final 20 advanced Java placement questions.

Output Questions

Sharpen your ability to predict Java output under pressure.

• Output Questions - Part 1 Interning, widening, precedence, and control-flow output puzzles.
• Output Questions - Part 2 Collection, String pool, and method-dispatch output puzzles.

Comparison Questions

Master the subtle differences interviewers love to test.

• Comparison Questions - Part 1 What really differs between String, StringBuilder, int, and Integer.
• Comparison Questions - Part 2 Advanced comparisons across containers and concurrency utilities.

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Section-wise Q&A

Topic-by-topic Java interview practice mapped to the syllabus.

• 1. Core Java Basics Core Java fundamentals — types, operators, control flow, and language rules.
• 2. Collections Framework List, Set, Map, sorting, and the Collections class.
• 3. OOP & Language Features OOP, inheritance, composition, and interface behavior.
• 4. Streams, Lambdas & Generics Streams, lambdas, functional interfaces, and generic quirks.
• 5. Exceptions & Memory Exception hierarchy, try-with-resources, JVM memory and GC.
• 6. Concurrency & Threads Threads, synchronization, locks, and concurrency utilities.