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Java Academy

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Become proficient in Java programming and develop powerful applications with Java Academy.

🤖 AI-Powered📚 104 courses👥 100,000+ learners⭐ 4.9 rating
Course Overview

Java: From First Class to Production-Grade Systems

Java has been the backbone of enterprise software, Android development, and large-scale backend systems for nearly three decades. It runs on the JVM, ships with a rich standard library, and powers everything from financial trading platforms to cloud microservices. This track builds genuine Java competence — starting with variables and control flow, and ending with JVM internals, virtual threads, and native compilation via GraalVM.

What You Will Learn

You will move from core syntax — variables, data types, loops, and methods — through object-oriented design with classes, inheritance, polymorphism, sealed classes, and records. The intermediate stages cover the full Collections framework, the java.time and NIO.2 APIs, lambda expressions, functional interfaces, and the Streams API including collectors, spliterators, and primitive streams. Later courses address Spring Boot configuration and dependency injection, Spring Data JPA, REST API validation, JUnit 5 integration testing, and JWT-based security. The advanced end of the track covers ExecutorService, locks, atomic variables, CompletableFuture, structured concurrency, virtual threads via Project Loom, JVM class loading and bytecode, GraalVM native image compilation, and performance profiling with JMH.

The Learning Path

Over 120 courses span A1 through C2. The A1 and A2 courses establish the fundamentals: the type system, casting, autoboxing, wrapper classes, arrays, conditionals, and methods. B1 covers object-oriented Java in depth — enums, inner classes, iterators, comparators, HashMap internals, exception handling, serialization, and build tools like Maven and Gradle. B2 introduces functional programming, generics with bounded wildcards, custom annotations, and a practical Spring Boot sequence ending in a Mini Project: REST API. The C1 courses are where concurrency and performance take center stage — parallel streams, the Java Memory Model, garbage collection, reflection, dynamic proxies, and structured concurrency. The track closes at C2 with the Foreign Function and Memory API, the lowest-level Java capability for interoperating directly with native code.

How It Works

Each course is split into short, focused lessons you complete in the built-in code editor with real-time feedback. An AI tutor is available whenever you get stuck, and mini projects at key milestones — Word Stats, Shape Hierarchy, Log Analyzer, REST API, and Parallel Stats — let you apply what you have learned before moving forward.

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How You'll Learn

🎯
Interactive Lessons
Hands-on coding exercises with real-time feedback
🤖
AI Tutor
Get instant help from our AI when you're stuck
💻
Built-in Editor
Write and run code directly in your browser
🏆
Certificate
Earn a certificate when you complete the course
Curriculum

104 Courses

Every course in the Java Academy learning path.

01

Introduction to Java

A13 lessons

Java is a high-level, object-oriented programming language introduced in 1995 by Sun Microsystems. Renowned for its "Write Once, Run Anywhe…

02

Scanner and Console Input

A14 lessonsPRO

Scanner and Console Input: Reading Input with Scanner, Reading Numbers and Lines, and more.

03

Hello Java & IDE Setup

A13 lessonsPRO

Start your Java journey: learn what programming is, how Java runs on the JVM, and what tools you will need next. This mini-course prepares…

04

Variables & Expressions Essentials

A13 lessonsPRO

Master Java variables and expressions: learn primitive types, declarations, assignment, printing values, and the basics of numeric expressi…

05

Java Type System & Casting

A24 lessonsPRO

Master Java's type system: primitive vs reference types, widening and narrowing conversions, explicit casting, and the instanceof operator…

06

Java Math & Number Formatting

A24 lessonsPRO

Explore the Math class, BigDecimal for financial precision, NumberFormat for locale-aware output, and practical numeric problem solving in…

07

Switch Expressions and Arrow Syntax

A24 lessonsPRO

Switch Expressions and Arrow Syntax: Arrow-Style switch, switch as an Expression, and more.

08

Text Blocks and Multiline Strings

A24 lessonsPRO

Text Blocks and Multiline Strings: Declaring Text Blocks, Indentation and Stripping, and more.

09

var and Local Type Inference

A24 lessonsPRO

var and Local Type Inference: Using var for Locals, When var Helps Readability, and more.

10

Wrapper Classes and Autoboxing

A24 lessonsPRO

Wrapper Classes and Autoboxing: Primitive vs Wrapper Types, Autoboxing and Unboxing, and more.

11

The Arrays Utility Class

A24 lessonsPRO

The Arrays Utility Class: Arrays.sort and Sorting, Arrays.binarySearch, and more.

12

Java Random and Math Utilities

A24 lessonsPRO

Java Random and Math Utilities: The Math Class, Generating Random Numbers, and more.

13

Reading Input with BufferedReader

A24 lessonsPRO

Read user and file input efficiently in Java.

14

Java Ternary and Conditional Expressions

A24 lessonsPRO

Write compact decisions with the conditional operator.

15

Java Char and Character Methods

A24 lessonsPRO

Work with individual characters using the Character class.

16

Formatting Output with printf

A24 lessonsPRO

Produce neatly formatted text with format specifiers.

17

Java Labeled Loops and Flow Control

A24 lessonsPRO

Control nested loops with break, continue, and labels.

18

Conditions I: If/Else Basics

A23 lessonsPRO

Make decisions in Java using if, else if, and else. Build clear boolean expressions with comparison and logical operators. Short, mobile-fr…

19

Conditions II: Operators & Switch

A23 lessonsPRO

Dive deeper into comparisons (==, !=, <, >, <=, >=) and boolean logic (&&, ||, !). Learn precedence, grouping with parentheses, short-circu…

20

Loops I: While & Do-While

A22 lessonsPRO

Learn while loops step by step: initialization, condition, update, and avoiding infinite loops. Practice small patterns that repeat actions…

21

Loops II: For & Patterns

A23 lessonsPRO

Master the for loop: initialization, condition, update in one line. Write counting loops, sums, and simple patterns. Learn break and contin…

22

Java Operators

A21 lessonPRO

Java offers us many operators to operate on the data we have. With the help of these operators, we can manipulate the data we have. They ar…

23

Strings in Java

A21 lessonPRO

The string data type is used in Java to hold our text data. Strings are reference data types, not primitive in Java. In this course, we wil…

24

Arrays I: 1D Arrays

A23 lessonsPRO

Learn 1D arrays: what they are, how to declare and create them, access and update elements, use length , and iterate with for and enhanced…

25

Arrays II: 2D Arrays

A26 lessonsPRO

Learn 2D arrays in Java: declare and create them, access rows and columns, and iterate with nested loops. Practice computing row/column sum…

26

Methods I: Basics

A23 lessonsPRO

Master the foundations of Java methods: signatures, parameters vs. arguments, calling conventions, and basic design. Short, focused lessons…

27

Methods II: Design & Reuse

A23 lessonsPRO

Design and reuse methods effectively: understand Java's pass-by-value semantics, choose between static and instance methods, and decompose…

28

Java Enums

B14 lessonsPRO

Learn how to define and use enums in Java: enum constants, fields, methods, switch expressions with enums, and the EnumSet/EnumMap collecti…

29

Java Records & Immutable Data

B14 lessonsPRO

Discover Java Records (Java 16+): creating immutable data carriers, compact constructors, custom methods on records, and when to use record…

30

StringBuilder and String Performance

B14 lessonsPRO

StringBuilder and String Performance: Why Strings Are Immutable, Building Strings with StringBuilder, and more.

31

BigDecimal and BigInteger

B14 lessonsPRO

BigDecimal and BigInteger: Why Not double for Money, Working with BigDecimal, and more.

32

The java.time Date and Time API

B14 lessonsPRO

The java.time Date and Time API: LocalDate, LocalTime, LocalDateTime, Instant and Duration, and more.

33

Java Optional

B14 lessonsPRO

Use Optional to eliminate NullPointerExceptions: creating, mapping, filtering, and consuming Optionals idiomatically in Java 17+.

34

Java String Deep Dive

B14 lessonsPRO

Go beyond basic strings: StringBuilder, StringJoiner, regular expressions, String.format, text blocks, and common string algorithm patterns.

35

Java Varargs, Overloading & Static Members

B14 lessonsPRO

Master method overloading resolution, varargs parameters, static fields and methods, and utility class design patterns in Java.

36

Java Inner Classes & Anonymous Classes

B14 lessonsPRO

Explore nested class variants: static nested classes, inner classes, local classes, anonymous classes, and when each variant is appropriate.

37

Java Iterators & Iterable

B14 lessonsPRO

Implement custom Iterable and Iterator interfaces to make your own data structures compatible with for-each loops and the Java Collections…

38

Java Comparators & Sorting

B14 lessonsPRO

Sort collections and arrays using Comparable, Comparator, method references, and multi-level sort chains in real-world data scenarios.

39

Java LinkedList & Deque

B14 lessonsPRO

Understand LinkedList internals, doubly-linked structure, Deque operations, stack simulation, and when LinkedList outperforms ArrayList.

40

Java TreeMap & TreeSet

B14 lessonsPRO

Master sorted collections: TreeMap's NavigableMap operations, TreeSet for unique sorted elements, subMap/headMap/tailMap, and Red-Black tre…

41

Java NIO.2 Path & Files API

B14 lessonsPRO

Navigate the modern java.nio.file API: Path creation, Files utility methods, directory walking with walkFileTree, watching directories with…

42

Java Serialization & Object Persistence

B14 lessonsPRO

Understand Java serialization: Serializable interface, transient fields, serialVersionUID, custom writeObject/readObject, and modern altern…

43

Sealed Classes and Interfaces

B14 lessonsPRO

Sealed Classes and Interfaces: Declaring Sealed Types, permits Clause, and more.

44

Pattern Matching for instanceof and Records

B14 lessonsPRO

Pattern Matching for instanceof and Records: Pattern Matching for instanceof, Record Patterns, and more.

45

Regular Expressions with Pattern and Matcher

B14 lessonsPRO

Regular Expressions with Pattern and Matcher: Compiling Patterns, Finding and Matching, and more.

46

HashMap Internals and equals/hashCode

B14 lessonsPRO

HashMap Internals and equals/hashCode: How HashMap Works, The equals/hashCode Contract, and more.

47

EnumMap, EnumSet and Advanced Enums

B14 lessonsPRO

EnumMap, EnumSet and Advanced Enums: Enums with Fields and Methods, Abstract Methods in Enums, and more.

48

Logging with SLF4J and Logback

B14 lessonsPRO

Logging with SLF4J and Logback: Why Structured Logging, SLF4J Facade and Loggers, and more.

49

Packages and Access Modifiers

B11 lessonPRO

Java uses access modifiers to limit the access of objects between each other. This can sometimes be at the class level as well as at the va…

50

Mini Project: Word Stats

B13 lessonsPRO

Build a small word statistics tool: tokenize text, normalize, count, and report top results. Plan first, implement next.

51

OOP I: Classes & Objects

B13 lessonsPRO

Learn the basics of classes and objects in Java. Create simple classes, instantiate objects, and understand their role in OOP.

52

OOP II: Practices

B13 lessonsPRO

Everyday OOP practices in Java: this keyword, readable toString, correct equals and hashCode, and practical tips for small apps.

53

Inheritance I

B13 lessonsPRO

Learn basic inheritance in Java: extend a base class, call super constructors, and reuse common behavior safely.

54

Abstractions & Interfaces

B13 lessonsPRO

Abstract classes and interfaces in Java: when to use them, how to declare, and how they guide design.

55

Mini Project: Shape Hierarchy

B13 lessonsPRO

Design and implement a tiny shape hierarchy with an abstract base, concrete shapes, and polymorphic behaviors.

56

Collections I: Lists & Sets

B13 lessonsPRO

Learn Java Lists and Sets: when to use each, basic operations, and simple iteration patterns.

57

Collections II: Maps & Algorithms

B13 lessonsPRO

Learn to use Maps for key→value lookups, frequency counting, and simple algorithms with lists and sets.

58

Exceptions I: Fundamentals

B13 lessonsPRO

Learn the basics of exception handling: try, catch, and finally blocks with simple examples.

59

Exceptions II: Practice

B13 lessonsPRO

Apply exception handling with custom exceptions, throw statements, and defensive coding.

60

Files & I/O I

B13 lessonsPRO

Learn Java NIO Path and Files classes: creating, checking, and deleting files safely.

61

Files & I/O II

B13 lessonsPRO

Learn Java object serialization: writing objects to files and reading them back.

62

Mini Project: Log Analyzer

B13 lessonsPRO

Build a simple log analyzer to read, parse, and summarize log files.

63

Build Tools: Maven and Gradle

B14 lessonsPRO

Build Tools: Maven and Gradle: Maven Project Structure, Maven Plugins and Goals, and more.

64

JDBC and Connection Pooling

B14 lessonsPRO

JDBC and Connection Pooling: JDBC Fundamentals, PreparedStatement, and more.

65

Java Stream Collectors Deep Dive

B24 lessonsPRO

Go beyond basic Streams: groupingBy, partitioningBy, toMap, counting, summarizingInt, joining, and building custom Collectors for complex a…

66

Java Method References

B24 lessonsPRO

Simplify lambda expressions using method references: static, instance, arbitrary-instance, and constructor references with real functional-…

67

Java Design Patterns: Creational

B24 lessonsPRO

Implement the four key creational patterns in Java: Singleton (thread-safe), Factory Method, Abstract Factory, and Builder with fluent APIs.

68

Java Design Patterns: Behavioral

B24 lessonsPRO

Master behavioral design patterns in Java: Observer, Strategy, Command, and Template Method with concrete use cases from real applications.

69

Functional Interfaces in Depth

B24 lessonsPRO

Functional Interfaces in Depth: Function and BiFunction, Supplier and Consumer, and more.

70

Primitive Streams

B24 lessonsPRO

Primitive Streams: IntStream and LongStream, Range and Aggregate Operations, and more.

71

Bounded Wildcards and PECS

B24 lessonsPRO

Bounded Wildcards and PECS: Upper Bounded Wildcards, Lower Bounded Wildcards, and more.

72

Interfaces & Generics

B23 lessonsPRO

Interfaces in practice and the basics of Java generics for safer, reusable code.

73

Java Custom Annotations

B24 lessonsPRO

Define custom annotations, retention policies, targets, and process them at runtime with reflection and at compile time with annotation pro…

74

Advanced Stream Operations & Spliterator

B24 lessonsPRO

Unlock advanced Stream features: flatMap on nested structures, peek for debugging, parallel stream pitfalls, Spliterator internals, and inf…

75

Spring Boot: Configuration & Dependency Injection

B24 lessonsPRO

Master Spring Boot auto-configuration, application properties, profiles, @Bean, @Component, @Service, @Repository, and constructor injectio…

76

Spring Data JPA: Entities & Repositories

B24 lessonsPRO

Map Java entities to database tables with JPA annotations, define Spring Data repositories, write JPQL and native queries, and handle relat…

77

Spring Boot REST API: Validation & Error Handling

B24 lessonsPRO

Build robust REST APIs: Bean Validation with @Valid, custom validators, global exception handling with @ControllerAdvice, and RFC 7807 prob…

78

Testing with JUnit 5: Parameterized & Integration Tests

B24 lessonsPRO

Go beyond basic unit tests: parameterized tests with @MethodSource, @CsvSource, Testcontainers for database integration, and Spring Boot te…

79

Java Security: Hashing, Encryption & JWT

B24 lessonsPRO

Implement security fundamentals in Java: MessageDigest for hashing, AES encryption, HMAC-SHA256, and JWT creation and verification without…

80

The Java Module System (JPMS)

B24 lessonsPRO

The Java Module System (JPMS): module-info.java, requires and exports, and more.

81

The Modern HTTP Client

B24 lessonsPRO

The Modern HTTP Client: java.net.http.HttpClient, Async Requests, and more.

82

GraalVM and Native Image

B24 lessonsPRO

GraalVM and Native Image: What Is GraalVM, Building a Native Image, and more.

83

Lambdas & Functional Interfaces

B23 lessonsPRO

Learn Java lambdas and functional interfaces.

84

Streams I: Pipelines

B23 lessonsPRO

Learn how to use Java Streams to process data with pipelines.

85

Spring Boot Kickoff

B23 lessonsPRO

Get started with Spring Boot: setup project, use starters, and run your first app.

86

Data & Services

B23 lessonsPRO

Learn how to use Spring Data JPA and H2 database with repositories.

87

Testing & Delivery

B23 lessonsPRO

Testing Spring apps with WebTestClient/JUnit, configuration, and packaging.

88

Mini Project: REST API

B24 lessonsPRO

Design, implement, and test a REST API with Spring Boot.

89

Java ExecutorService & Thread Pools

C14 lessonsPRO

Manage thread life cycles with ExecutorService: fixed, cached, and scheduled thread pools, submitting Callable tasks, and handling Future r…

90

Java Locks & Atomic Variables

C14 lessonsPRO

Go beyond synchronized: ReentrantLock, ReadWriteLock, StampedLock, AtomicInteger, AtomicReference, and lock-free data structure patterns.

91

Parallel Streams and Performance

C14 lessonsPRO

Parallel Streams and Performance: Creating Parallel Streams, When Parallelism Helps, and more.

92

Java Memory Management & Garbage Collection

C14 lessonsPRO

Understand the JVM memory model: heap regions (Young/Old/Metaspace), GC algorithms (G1, ZGC), memory leaks, profiling with JVisualVM, and t…

93

Java CompletableFuture & Async Pipelines

C14 lessonsPRO

Compose asynchronous computations with CompletableFuture: thenApply, thenCompose, allOf, anyOf, exceptionally, and building non-blocking pi…

94

Java Reflection & Dynamic Proxies

C14 lessonsPRO

Use the Reflection API to inspect and invoke classes at runtime, create dynamic proxies, and understand how frameworks like Spring use refl…

95

JVM Internals: Classloading & Bytecode

C14 lessonsPRO

Peek inside the JVM: class loading phases, the bootstrap/extension/application loader hierarchy, bytecode inspection with javap, and JIT co…

96

Virtual Threads (Project Loom)

C14 lessonsPRO

Virtual Threads (Project Loom): What Are Virtual Threads, Creating Virtual Threads, and more.

97

Structured Concurrency

C14 lessonsPRO

Structured Concurrency: The Structured Concurrency Model, StructuredTaskScope, and more.

98

Microbenchmarking with JMH

C14 lessonsPRO

Microbenchmarking with JMH: Why JMH, Writing a Benchmark, and more.

99

Java Performance Profiling and Tuning

C14 lessonsPRO

Java Performance Profiling and Tuning: Identifying Bottlenecks, Java Flight Recorder, and more.

100

Streams II: Performance & Pitfalls

C13 lessonsPRO

Learn advanced behaviors of Streams including ordering and short-circuiting.

101

Concurrency I

C12 lessonsPRO

Introduction to Java concurrency with Threads, Executors, and synchronization.

102

Concurrency II

C13 lessonsPRO

Advanced concurrency: synchronization, locks, atomics, and common issues.

103

Mini Project: Parallel Stats

C13 lessonsPRO

Build a project that calculates statistics in parallel using streams and concurrency.

104

The Foreign Function and Memory API

C24 lessonsPRO

The Foreign Function and Memory API: Why FFM over JNI, MemorySegment and Arena, and more.

FAQ

Frequently Asked Questions

Is the Java Academy course free?

Yes. You can start the Java Academy course for free and complete its interactive lessons at no cost. An optional PRO subscription unlocks advanced AI tools and a shareable certificate.

Do I need prior experience to learn JAVA?

No. The course begins with the fundamentals and gradually moves to more advanced topics, so you can start even with no prior JAVA experience.

How will I learn JAVA on CoddyKit?

You learn by doing. Short interactive lessons pair a clear explanation with a hands-on coding exercise that runs in real time, and a 24/7 AI tutor gives personalized help whenever you get stuck.

Do I get a certificate for completing Java Academy?

Yes. PRO learners can take an exam and earn a shareable certificate of completion with a verifiable code for the Java Academy course.

Can I learn JAVA on my phone?

Yes. CoddyKit is available on the web and as native iOS and Android apps, so you can learn JAVA on any device and your progress syncs across them.

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