Track
java
Java
36 lessons: JVM, OOP, collections, modern Java—compiled Java playground and 108 MCQs.
- Mode
- server_compiled
- Practice
- Compiled runner
- Lessons
- 36 units
Before you start
The Java language on the JVM: strong typing, OOP, collections, exceptions, and modern features (streams, records).
Enterprise hiring, Android backends, and large codebases still rely on Java patterns and the Spring ecosystem.
Spring Boot APIs, banking systems, Android (with Kotlin), and batch/data pipelines on the JVM.
36 lessons with compiled Java playground (javac + java on dev runner), interview prep, and 108 MCQs.
After programming fundamentals (variables, loops, functions)—often after JavaScript or Python, before Spring.
Lesson order
Sequential — follow top to bottom36 lessons are live in this track. Start from step 01 for the smoothest path.
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01 intro Introduction to Java
beginner
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02 what-is-java What is Java?
beginner
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03 java-vs-other-languages Java vs other languages
beginner
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04 jvm-bytecode-overview JVM and bytecode overview
beginner
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05 playground-workflow Playground workflow
beginner
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06 class-main-method Class and main method
beginner
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07 variables-types Variables and types
beginner
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08 operators Operators and expressions
beginner
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09 strings Strings
beginner
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10 control-flow Control flow
beginner
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11 methods Methods
beginner
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12 classes-objects Classes and objects
beginner
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13 constructors Constructors
beginner
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14 encapsulation Encapsulation
intermediate
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15 inheritance Inheritance
intermediate
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16 polymorphism Polymorphism
intermediate
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17 interfaces Interfaces
intermediate
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18 arrays Arrays
beginner
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19 arraylist ArrayList
beginner
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20 hashmap HashMap
intermediate
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21 loops-iterators Loops and iterators
beginner
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22 generics-intro Generics introduction
intermediate
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23 equals-hashcode equals and hashCode
intermediate
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24 exceptions-try-catch Exceptions and try-catch
beginner
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25 checked-unchecked Checked vs unchecked exceptions
intermediate
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26 file-io-basics File I/O basics
intermediate
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27 packages-imports Packages and imports
beginner
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28 static-final static and final
intermediate
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29 streams-lambdas Streams and lambdas
intermediate
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30 optional-records Optional and records
intermediate
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31 jdbc-intro JDBC introduction
intermediate
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32 maven-gradle-intro Maven and Gradle intro
intermediate
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33 interview-essentials Interview essentials
intermediate
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34 production-checklist Production checklist
advanced
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35 spring-teaser Spring Boot teaser
intermediate
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36 summary Track summary
beginner
Open →