java-tutorial

4) Methods

Goal

Write reusable code with methods, parameters, return values, and overloading.

A simple method

static int add(int a, int b) {
    return a + b;
}

Call it:

int result = add(2, 3);

void methods

static void greet(String name) {
    System.out.println("Hello, " + name);
}

Method overloading

Same method name, different parameter types or counts:

static int add(int a, int b) { return a + b; }
static double add(double a, double b) { return a + b; }

Pass-by-value (important!)

Java is pass-by-value.

• For primitives: the value is copied.
• For references: the reference value is copied (two variables can point to the same object).

Exercises

1. Write max(int a, int b).
2. Write isPrime(int n).
3. Write reverse(String s).

Table of contents

1. Getting Started: Install, run, and your first program
2. Java Basics: types, variables, operators, formatting
3. Control Flow: if/switch/loops
4. Methods: parameters, return values, overloading
5. OOP: classes, objects, encapsulation
6. Inheritance & Polymorphism (and when not to use them)
7. Interfaces, abstract classes, and design basics
8. Exceptions and error handling
9. Strings, files, and I/O basics
10. Collections: List/Set/Map and Big-O intuition
11. Generics (the useful parts)
12. Lambdas & Streams
13. Dates and time (java.time)
14. Testing with JUnit 5 (basics)
15. Concurrency: threads, executors, futures
16. JVM basics: memory, GC, performance habits
17. Build tools: Maven essentials (recommended)
18. Next steps: projects to build