Java Code Typing

Lambda Arrows & Method References

The -> arrow and :: separator in functional positions

Annotations

At-signs, annotation arguments, and stacked markers

Stream Chain Punctuation

Fluent dots, collectors, and closing parenthesis stacks

Switch Arrows & Yield Blocks

case X -> arms, comma-grouped labels, and yield bodies

Checkpoint: Symbol Fluency

Every Java glyph cluster from this module in one longer drill

Keywords

Reserved words plus the modern record and sealed additions

Declarations

Records, sealed interfaces, final classes, and var

Optional Idioms

map, flatMap, and orElseThrow instead of null checks

Exception Keywords

try, catch, finally, throw, and throws in rhythm

Text Blocks & Formatting

Triple-quoted blocks, formatted, and printf specifiers

Idiomatic One-Liners

Streams, collectors, and method references at a glance

Checkpoint: Keywords & Idioms

A small service class mixing this module's material

Control Flow

Enhanced for, switch expressions, and instanceof patterns

Functions & Methods

Generic signatures, Optional returns, and varargs

Records & Compact Constructors

Validation and normalisation inside a compact constructor

Sealed Hierarchy & Exhaustive Switch

permits clauses, record patterns, and when guards

try-with-resources

Auto-closing streams and wrapping checked exceptions

Maps & Aggregation

computeIfAbsent, merge, and getOrDefault on real data

Realistic Snippet

A CSV sales report loaded, grouped, and printed

Checkpoint: Real Snippets

A generic Result type built from sealed records and switch

Speed Run: Stream Report

groupingBy, summingDouble, sorted, and limit without pausing

Speed Run: CompletableFuture Fan-Out

supplyAsync, allOf, and join across a thread pool

Speed Run: Concurrent Counter

ConcurrentHashMap merge and AtomicLong under load

Speed Run: JUnit 5 Suite

BeforeEach fixtures, assertEquals, and assertThrows

Speed Run: Comparators & Iterable

Chained comparators behind an Iterable leaderboard

Checkpoint: Sustained Speed

A p95 latency monitor typed in one continuous run

Assessment Sim 1: Task Tracker

A complete tracker built on records, sealed types, and streams

Assessment Sim 2: Word Histogram

A full Files.lines program that ranks word frequencies

Assessment Sim 3: RPN Calculator

A Deque evaluator with underflow and divide-by-zero paths

Assessment Sim 4: Inventory Ledger

A stock-movement program that rejects oversell

Checkpoint: Java Mastery Final

An end-to-end traffic and latency report -- the graded final