Master Java syntax, primitive types, operators, control flow, arrays, methods, and exception handling.

Build with classes, interfaces, inheritance, polymorphism, SOLID principles, and common design patterns.

Master ArrayList, HashMap, HashSet, generics, Comparable, Comparator, and the Collections utility class.

Write expressive Java with lambda expressions, functional interfaces, Stream API, Optional, and method references.

Understand Java threads, synchronization, ExecutorService, volatile, memory model, and modern Java features.