Skip to content

Java Basics - Reference Handout

What You'll Learn Today

  • Set up your Java development environment
  • Understand what Java is and why it's important
  • Write and run your first Java programs
  • Participate in your first team meeting

Java Quick Facts

What is Java?

  • Programming Language: Used to create software applications
  • Platform Independent: Code runs on Windows, Mac, Linux
  • Compiled Language: Code is translated to bytecode before running
  • Popular Uses: Web applications, mobile apps, enterprise software

Key Java Concepts

  • JDK: Java Development Kit (tools for writing Java)
  • JVM: Java Virtual Machine (runs your programs)
  • Bytecode: Translated version of your code that JVM understands

Basic Java Program Structure

public class ClassName {
    public static void main(String[] args) {
        // Your code goes here
        System.out.println("Hello, World!");
    }
}

Breaking it Down:

  • public class ClassName: Creates a container for your code
  • public static void main: The starting point of your program
  • String[] args: Allows command line input (ignore for now)
  • System.out.println(): Prints text to the screen
  • //: Creates a comment (ignored by computer)

Essential Commands

System.out.println("Text here");  // Prints and moves to next line
System.out.print("Text here");    // Prints without moving to next line

Special Characters

  • \n: New line
  • \t: Tab space
  • \": Quotation mark inside text

Example:

System.out.println("Hello\nWorld");  // Prints Hello on one line, World on next
System.out.println("She said \"Hi\"");  // Prints: She said "Hi"

Naming Rules

Class Names

  • Start with capital letter
  • Use PascalCase: MyFirstClass, StudentRecord
  • No spaces, no special characters except underscore

Method Names

  • Start with lowercase letter
  • Use camelCase: printMessage, calculateTotal

Good Examples:

  • ✅ HelloWorld
  • ✅ PersonalIntroduction
  • ✅ MyCalculator

Bad Examples:

  • ❌ hello world (space)
  • ❌ my-class (hyphen)
  • ❌ 2ndProgram (starts with number)

Today's Programs

Program 1: Hello World

Purpose: Learn basic structure and run first program 

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Program 2: Personal Introduction

Purpose: Practice printing multiple lines Your Task: Create a program that prints: - Your name - Your age - Your favorite hobby - Why you're interested in programming

Program 3: ASCII Art Challenge

Purpose: Practice with multiple print statements Your Task: Print your initials using asterisks (*)

Meeting Participation Tips

What to Do:

  • ✅ Listen actively
  • ✅ Take notes on technical terms you don't understand
  • ✅ Observe how team members communicate
  • ✅ Ask questions during appropriate breaks

What to Avoid:

  • ❌ Using your phone
  • ❌ Interrupting ongoing discussions
  • ❌ Feeling pressured to contribute immediately

Troubleshooting Common Issues

Error: "Could not find or load main class"

Solution: Make sure your class name matches your file name exactly

Error: "';' expected"

Solution: Check that every statement ends with a semicolon (;)

Error: "cannot find symbol"

Solution: Check spelling of commands like System.out.println

Program Doesn't Print Anything

Solution: Make sure your text is inside quotation marks

IntelliJ IDEA Quick Reference

Essential Buttons/Actions:

  • Green Play Button (â–ļī¸): Run your program
  • Red Square (⏚ī¸): Stop running program
  • Ctrl + S: Save your work
  • Ctrl + Z: Undo last action

Project Structure:

JavaInternship/
├── src/
│   ├── HelloWorld.java
│   ├── PersonalIntro.java
│   └── (your other programs)

End of Day Checklist

  • Java JDK installed and working
  • IntelliJ IDEA installed and configured
  • Successfully ran "Hello World" program
  • Created personal introduction program
  • Attended first team meeting
  • Attempted ASCII art challenge
  • Understand basic Java program structure

Questions for Self-Reflection

  1. What was the most challenging part of today?
  2. What concept do you want to understand better?
  3. How did the team meeting help you understand the work environment?
  4. What questions do you have for tomorrow?

Homework (Optional)

Research Topic: "What are variables in programming?" Goal: Come prepared to discuss what you learned

Resources: - Oracle Java Documentation: https://docs.oracle.com/javase/tutorial/ - Search: "Java variables tutorial"

Tomorrow's Preview: Variables and Data Types

  • Learn to store and use information in your programs
  • Make programs that can work with numbers and text
  • Create a simple calculator

Bring Tomorrow: - This handout - Any questions from today - Curiosity about making programs more interactive!