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SkillSnap Official GuideUpdated 7/24/2026
Java
The enterprise standard. Master modern syntax like Records, Pattern Matching, and Virtual Threads to write concise, high-performance code.
Modern Syntax (Java 14+)
Local variable type inferencevar
Immutable data carrier (No boilerplate)record Point(x, y)
Text Blocks (Multi-line strings)""" ... """
Switch Expressions (Return values)switch -> / yield
Pattern Matching (No explicit cast)instanceof String s
Restrict class inheritance hierarchysealed / permits
Streams & Functional
Create immutable list instantlyList.of()
Collect to list (Java 16+).stream().toList()
Transform / Select data.map() / .filter()
Cleaner lambda syntax (String::toUpperCase):: (Method Ref)
Safe value unpackingOptional.orElseThrow()
Avoid boxing overhead for numbersIntStream
Concurrency & Threads
Lightweight, high-throughput (Java 21)Virtual Threads
Async / Non-blocking pipelinesCompletableFuture
Lock-free thread safetyAtomicInteger
Block-level locking (Prefer over methods)synchronized (obj)
Core APIs (IO & Time)
Modern Date/Time (Avoid java.util.Date)java.time
UTC Timestamp for loggingInstant
Simple file reading (NIO.2)Files.readString()
Native HTTP Client (Java 11+)HttpClient
Performance & Memory
Concatenate strings in loopsStringBuilder
High-perf Map for Enum keysEnumMap
Modern Garbage CollectorsG1GC / ZGC
Always set Heap Size in production-Xmx / -Xms
Spring Framework (Standard)
Best practice (Avoid @Autowired on fields)Constructor Injection
Controller + ResponseBody@RestController
Environment-specific beans@Profile
Best Practices
Fail fast on null inputsObjects.requireNonNull()
Store passwords (clearable from memory)char[]
Auto-close streams/filestry-with-resources