Beginner9 lessons~14 h

Java: From Zero to Objects

Java asks you to type more than Python does, and every extra word is there for a reason — the compiler catches a whole category of mistakes before your program ever runs. Nine lessons take you from Hello World to a working student grade manager built out of classes, and we stop at every pothole beginners fall into instead of stepping around it.

Module 01

Module 1 · Getting Your First Java Program to Run

The main method, types, Scanner input — and the traps that are unique to Java.

  1. Hello World and Those Five Mysterious LinesWhy Java needs so much just to print one line, and what each word is actually doing.
  2. Variables and Types: Say What It Is Firstint/double/String, the integer division trap, and final constants.
  3. Scanner Input and Formatted OutputThe leftover-newline bug that every single Java beginner hits exactly once.
Module 02

Module 2 · Control Flow and Collections

if/switch, loops, arrays vs ArrayList, and HashMap.

  1. if / switch, and Why == Lies About StringsThe difference between == and equals — the most-asked Java interview question, for good reason.
  2. Loops: The Three-Part for and the Enhanced forExecution order, nested loops, and what to seed a max variable with.
  3. Arrays, ArrayList, and HashMapFixed size vs growable, what the angle brackets mean, and how to print an array without garbage.
Module 03

Module 3 · Objects and a Real Project

Classes and objects, encapsulation, static — then assemble a student grade manager.

  1. Classes and Objects: Keeping Related Data TogetherWhy three parallel arrays are a disaster, and what this means in a constructor.
  2. Encapsulation and staticprivate plus getters and setters, and the real reason main has to be static.
  3. Project: A Student Grade ManagerStudent + StudentManager + Main, split into three layers, running as a real command-line app.
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