Interview Preparation

Resources to help you prepare for Java interviews and quickly review key concepts.

Available Resources

• Quick Reference

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  One-page cheat sheet with all major features organized by version.

  View Cheat Sheet

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Top Interview Topics by Version

Java 8

• Lambda expressions and functional interfaces
• Stream API (intermediate vs terminal operations)
• Optional (proper usage, anti-patterns)
• Date/Time API (LocalDate vs ZonedDateTime)

Java 11

• var keyword (when to use, when to avoid)
• HTTP Client API
• New String methods

Java 17

• Records (vs classes, limitations)
• Sealed classes (with pattern matching)
• Pattern matching for instanceof
• Switch expressions

Java 21

• Virtual Threads (vs platform threads, when to use)
• Pattern matching for switch
• Record patterns
• Sequenced Collections

Java 25

• Primitive type patterns
• Flexible constructor bodies
• Scoped Values (vs ThreadLocal)

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Quick Tips

For Whiteboard Coding

• Use var to save time writing types
• Prefer streams for collection processing
• Use records for simple data holders
• Show you know the latest features

For System Design

• Mention Virtual Threads for high-concurrency services
• Discuss sealed classes for domain modeling
• Reference pattern matching for cleaner conditionals