Foundations

15 labs from your first Hello World to a complete inventory system using OOP, streams, generics, concurrency, and NIO.2.

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Lab
Key Concepts

1

compile, JVM, main method, System.out

2

int, double, char, boolean, casting

3

String methods, immutability, StringBuilder

4

arrays, 2D arrays, Arrays utility, sorting

5

switch expressions, loops, recursion, FizzBuzz

6

fields, constructors, records, Builder pattern

7

extends, override, super, sealed classes

8

interface, default/static methods, functional, Strategy/Observer

9

ArrayList, HashSet, HashMap, PriorityQueue

10

checked/unchecked, custom hierarchy, chaining, Result type

11

Path, Files, walk, WatchService, log analyzer

12

type parameters, bounds, wildcards, PECS, repository

13

filter/map/collect, groupingBy, flatMap, parallel, sales pipeline

14

threads, ExecutorService, CompletableFuture, virtual threads

15

all concepts combined, CLI app, CSV persistence

Runtime: Java 21 (Eclipse Temurin) · Docker: zchencow/innozverse-java:latest

🐳 Quick Start

docker run --rm zchencow/innozverse-java:latest java -e 'class H{public static void main(String[]a){System.out.println("Hello, Java 21!");}}'

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