What You Should Know Before Learning Java

5 minute read

Before we install Java and start writing code, let’s make sure you have the right foundation. Don’t worry — you don’t need any programming experience. This chapter covers the basic computer skills you’ll need and sets expectations for the journey ahead.

Prerequisites — What You Actually Need

Here’s the honest truth about what you need to start learning Java:

Requirement Details
Programming experience ❌ None required — we start from absolute zero
Computer Any modern computer — Windows, macOS, or Linux
RAM 4GB minimum, 8GB recommended
Disk space ~2GB for JDK + IDE
Internet Needed to download JDK and IDE
Math Basic arithmetic (add, subtract, multiply, divide)
English Ability to read English (you’re already doing this!)

Basic Computer Skills You Need

Opening the Terminal (Command Line)

Throughout this tutorial, you’ll use the terminal (also called command line, console, or shell) to compile and run Java programs. Here’s how to open it:

OS How to Open Terminal
Windows Press Win + R, type cmd, press Enter. Or search “PowerShell” in the Start menu
macOS Press Cmd + Space, type “Terminal”, press Enter
Linux Press Ctrl + Alt + T or search “Terminal” in your app menu

The terminal is where you type text commands instead of clicking buttons. It looks like this:

$ _

The $ is called a prompt — it’s the terminal telling you “I’m ready for your command.” You type after the $ and press Enter.

Tip: In this tutorial, all terminal commands start with $. Don’t type the $ — it just means “this is a terminal command.”

Understanding File Paths

When you save files on your computer, they’re organized in folders (also called directories). A file path tells you exactly where a file is located.

Absolute path — the full location from the root:

# macOS/Linux
/home/john/projects/HelloWorld.java

# Windows
C:\Users\John\Projects\HelloWorld.java

Relative path — location relative to where you currently are:

# If you're already in /home/john/projects/
HelloWorld.java

# If you're in /home/john/
projects/HelloWorld.java

Here are the only terminal commands you need to know for now:

Command What It Does Example
cd Change directory (move to a folder) cd projects
ls (Mac/Linux) or dir (Windows) List files in current folder ls
pwd (Mac/Linux) Print current directory pwd
mkdir Create a new folder mkdir projects

Example workflow:

$ cd ~                    # Go to your home directory
$ mkdir java-projects     # Create a folder for Java code
$ cd java-projects        # Enter the folder
$ pwd                     # Verify where you are
/home/john/java-projects

What Is a Compiler and Runtime?

Before we start coding, let’s understand two important concepts in plain English:

Compiler

A compiler is a program that translates your human-readable code into something the computer can execute. In Java, the compiler (javac) turns your .java files into .class files (bytecode).

Think of it like a translator: you write instructions in Java (English), and the compiler translates them into bytecode (a universal language all JVMs understand).

Runtime

A runtime is the environment that actually executes your compiled code. In Java, the runtime is the JVM (Java Virtual Machine).

Think of the compiler as the translator and the runtime as the interpreter who actually carries out the instructions.

You write Java code → Compiler translates → Runtime executes
     (chef writes recipe)   (recipe printed)   (cook follows recipe)

Setting Expectations

How Long Will This Take?

Learning Goal Estimated Time
Core Java Basics (this module — 26 chapters) 2–3 weeks (1–2 hours/day)
+ OOP (Module 2) + 3–4 weeks
+ Collections + Streams (Modules 5–6) + 2–3 weeks
Job-ready with Spring Boot (through Module 13) ~4–5 months total
Full series (all 17 modules) ~6 months

These are estimates for consistent daily practice of 1–2 hours. Everyone learns at a different pace — and that’s perfectly fine.

What Will You Build First?

In this module alone, you’ll build:

  • ✅ Your first Java program (Hello World)
  • ✅ A temperature converter
  • ✅ A grade calculator
  • ✅ A simple calculator with user input
  • ✅ A number guessing game
  • ✅ A BMI calculator
  • ✅ Pattern printers (triangles, pyramids)
  • ✅ Recursive problem solvers (factorial, Fibonacci)

How This Tutorial Series Is Structured

Our Complete Java Tutorial Series is organized into 17 modules with 257 chapters:

  1. Core Java Basics ← You are here
  2. Object-Oriented Programming
  3. Arrays, Strings & Utilities
  4. Exception Handling
  5. Collections & Generics
  6. Functional Java & Streams
  7. File I/O
  8. Concurrency & Multithreading
  9. Logging
  10. Java Mail
  11. Unit Testing
  12. Build Tools (Maven & Gradle)
  13. Spring Boot
  14. Spring Cloud & Microservices
  15. Java for AI
  16. JVM Internals & Performance
  17. Modern Java (8→21)

Each module builds on the previous ones. Read in order — skipping ahead usually leads to confusion.

Tips for Success

  1. Type every code example — Don’t copy-paste. Typing builds muscle memory and helps you notice patterns.

  2. Run every program — Don’t just read code. Compile it. Run it. See the output. Then change something and run it again.

  3. Make mistakes on purpose — Change a variable name, remove a semicolon, use the wrong type. See what error you get. Learning to read error messages is a superpower.

  4. Don’t memorize — understand — You don’t need to memorize every keyword. Focus on understanding why things work. You can always look up syntax.

  5. Take breaks — If you’re stuck on a concept for more than 30 minutes, take a break. Walk around. Come back with fresh eyes.

  6. Build your own projects — After each area (e.g., control flow), try building something small on your own. A calculator, a quiz game, a unit converter.

Summary

Topic Key Point
Programming experience Not required — we start from zero
Computer requirements Any OS, 4GB+ RAM, 2GB disk space
Terminal You’ll use it to compile and run Java — learn cd, ls, mkdir
Compiler Translates Java code to bytecode (javac)
Runtime Executes bytecode on the JVM (java)
Time investment 2–3 weeks for this module at 1–2 hours/day

What’s Next?

It’s time to get Java installed on your machine. Pick your operating system:

Updated:

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