Complete Java course: JVM and setup, core syntax, OOP, exceptions, collections and generics, lambdas and streams, modern Java 21–25, concurrency, JDBC, Maven/Gradle and JUnit, Spring Boot REST APIs, JPA and Spring Security.
Each lecture has detailed notes, code examples, interview questions and practice exercises. Follow them in order, or jump to the topic you need.
Learn what Java is, how write-once-run-anywhere works, the difference between JDK, JRE and JVM, bytecode, JIT compilation and garbage collection. Install a JDK, set JAVA_HOME, write your first Hello World with javac and java, use jshell, and try Java 25 compact source files.
Learn Java variables, the eight primitive data types and their ranges, wrapper classes and autoboxing, var type inference, literals, final constants, operators and precedence, integer division and overflow, implicit vs explicit type casting, and Scanner input — with examples and interview questions.
Master Java control flow: if/else and nested conditions, classic switch vs switch expressions with arrow labels and yield, pattern matching for switch (Java 21), for, enhanced for, while and do-while loops, break, continue and labels, common loop patterns and interview pattern-printing programs.
Learn Java methods (parameters, return types, pass-by-value, overloading, varargs, recursion), one and two-dimensional arrays with the Arrays utility class, and Strings: immutability, the string pool, equals vs ==, common String methods, StringBuilder, text blocks and String.format.
Learn Java classes and objects, fields and methods, constructors and overloading, the this keyword, access modifiers, encapsulation with getters and setters, static members, initialization blocks, object lifecycle, equals/hashCode/toString, Java records and packages — with examples and interview questions.
Master Java inheritance, super, method overriding, runtime polymorphism and dynamic dispatch, abstract classes, interfaces with default, static and private methods, sealed classes (Java 17), composition over inheritance and SOLID principles, with interview questions and a hands-on payroll project.
Master Java exception handling: the Throwable hierarchy, checked vs unchecked exceptions, try-catch-finally, multi-catch, try-with-resources, throw vs throws, custom exceptions, exception chaining, helpful NullPointerException messages and Optional, with best practices and interview questions.
Master the Java Collections Framework and Generics: ArrayList vs LinkedList, HashSet vs TreeSet, HashMap vs TreeMap, how HashMap works internally, Queue and Deque, Java 21 sequenced collections, List.of immutable factories, Comparable vs Comparator, bounded types, wildcards and type erasure.
Master functional programming in Java: lambda expressions, functional interfaces (Predicate, Function, Consumer, Supplier), method references, the Java Streams API with filter, map, flatMap, reduce and Collectors, Optional, parallel stream caveats and Stream Gatherers (final in Java 24, in Java 25 LTS).
Learn modern Java from 17 to 25: records and compact constructors, sealed classes, pattern matching for instanceof and switch, record patterns, unnamed variables, text blocks, var, sequenced collections, virtual threads and the new Java 25 features, with a clear final-vs-preview map, interview questions and a hands-on exercise.
Master Java concurrency and multithreading: threads vs processes, Runnable and Callable, thread lifecycle, race conditions, synchronized, volatile, ReentrantLock, atomic classes, ExecutorService thread pools, CompletableFuture, concurrent collections, deadlocks and Java 21 virtual threads, with interview questions.
Learn Java file I/O and JDBC end to end: java.io vs java.nio.file, the Path and Files API, reading and writing files, walking directories, serialization caveats, JSON with Jackson, PreparedStatement against SQL injection, ResultSet, transactions, HikariCP connection pooling and the DAO pattern.
Learn Java build tools and testing end to end: Maven pom.xml, lifecycle, dependencies and BOMs, Gradle with Kotlin DSL, JUnit 5 (Jupiter) assertions, lifecycle and parameterized tests, Mockito mocks and verification, AssertJ, JaCoCo code coverage and the TDD workflow, with interview questions.
Build REST APIs with Spring Boot 4: Spring ecosystem, dependency injection and IoC, Spring Initializr, @RestController, path variables and request params, DTOs with records, Jakarta Bean Validation, service and repository layers, @ControllerAdvice with ProblemDetail, profiles and MockMvc tests.
Learn Spring Data JPA and Hibernate (entities, relationships, derived queries, pagination, the N+1 problem, Flyway migrations), then secure your Spring Boot REST API with Spring Security, BCrypt and JWT authentication, and finally package a jar, build a Docker image and deploy to production with a checklist and interview questions.