feat: Add Day 01 - Java Basics and Setup with Hello World examples

Author: Zemerik

Day 01 - Java Basics and Setup/BasicStructure.java

@@ -0,0 +1,64 @@
+/**
+ * Day 01 - BasicStructure.java
+ * Understanding Java Program Structure
+ * 
+ * This program demonstrates the essential components of a Java program
+ * and explains each part in detail.
+ */
+
+// Import statements (we'll learn more about these later)
+import java.util.Date;
+
+/**
+ * This class demonstrates the basic structure of a Java program
+ * Class names should start with a capital letter and use CamelCase
+ */
+public class BasicStructure {
+    
+    // Class-level variables (we'll learn about these in detail later)
+    private static final String PROGRAM_NAME = "Basic Structure Demo";
+    
+    /**
+     * Main method - the entry point of the program
+     * This method must be public, static, and void
+     * @param args command line arguments
+     */
+    public static void main(String[] args) {
+        // Method calls and program logic go here
+        printProgramInfo();
+        demonstrateStructure();
+        showCurrentTime();
+    }
+    
+    /**
+     * This method prints information about the program
+     * Methods should have descriptive names and do one thing well
+     */
+    public static void printProgramInfo() {
+        System.out.println("=== " + PROGRAM_NAME + " ===");
+        System.out.println("This program demonstrates Java structure.");
+        System.out.println();
+    }
+    
+    /**
+     * Demonstrates different parts of Java structure
+     */
+    public static void demonstrateStructure() {
+        System.out.println("Java Program Structure:");
+        System.out.println("1. Package declaration (optional)");
+        System.out.println("2. Import statements");
+        System.out.println("3. Class declaration");
+        System.out.println("4. Class variables and methods");
+        System.out.println("5. Main method (entry point)");
+        System.out.println();
+    }
+    
+    /**
+     * Shows how to use imported classes
+     */
+    public static void showCurrentTime() {
+        Date currentTime = new Date();
+        System.out.println("Current time: " + currentTime);
+        System.out.println("Program completed successfully!");
+    }
+} 

Day 01 - Java Basics and Setup/Comments.java

@@ -0,0 +1,78 @@
+/**
+ * Day 01 - Comments.java
+ * Understanding Comments in Java
+ * 
+ * This program demonstrates the three types of comments in Java:
+ * 1. Single-line comments
+ * 2. Multi-line comments
+ * 3. Documentation comments (JavaDoc)
+ */
+
+/**
+ * This is a documentation comment (JavaDoc)
+ * It's used to generate documentation for your code
+ * 
+ * @author Your Name
+ * @version 1.0
+ * @since 2025
+ */
+public class Comments {
+    
+    // This is a single-line comment
+    // It starts with // and continues to the end of the line
+    
+    /*
+     * This is a multi-line comment
+     * It starts with /* and ends with */
+    /*
+     * You can write multiple lines
+     * of comments like this
+     */
+    
+    /**
+     * Main method - demonstrates different comment types
+     * @param args command line arguments
+     */
+    public static void main(String[] args) {
+        // Print information about comments
+        System.out.println("=== Java Comments Demo ===");
+        System.out.println();
+        
+        // Demonstrate single-line comments
+        System.out.println("1. Single-line comments:");
+        System.out.println("   // This is a single-line comment");
+        System.out.println();
+        
+        // Demonstrate multi-line comments
+        System.out.println("2. Multi-line comments:");
+        System.out.println("   /* This is a multi-line comment */");
+        System.out.println();
+        
+        // Demonstrate documentation comments
+        System.out.println("3. Documentation comments:");
+        System.out.println("   /** This is JavaDoc comment */");
+        System.out.println();
+        
+        // Show best practices
+        System.out.println("Best Practices:");
+        System.out.println("- Use comments to explain WHY, not WHAT");
+        System.out.println("- Keep comments up to date with code changes");
+        System.out.println("- Use meaningful variable and method names");
+        System.out.println("- Write self-documenting code when possible");
+        
+        // Calculate and display a simple example
+        int number = 42; // This is the answer to everything
+        System.out.println("\nExample: The number is " + number);
+    }
+    
+    /**
+     * This method demonstrates how to use JavaDoc comments
+     * for documenting methods
+     * 
+     * @param name the name to greet
+     * @return a greeting message
+     */
+    public static String greet(String name) {
+        return "Hello, " + name + "!";
+    }
+} 

Day 01 - Java Basics and Setup/HelloWorld.java

@@ -0,0 +1,30 @@
+/**
+ * Day 01 - HelloWorld.java
+ * Your first Java program
+ * 
+ * This program demonstrates the basic structure of a Java application
+ * and shows how to print text to the console.
+ */
+public class HelloWorld {
+    
+    /**
+     * The main method is the entry point of any Java application
+     * @param args command line arguments (not used in this example)
+     */
+    public static void main(String[] args) {
+        // This is a single-line comment
+        System.out.println("Hello, World!");
+        
+        // Print multiple lines
+        System.out.println("Welcome to Java Programming!");
+        System.out.println("This is Day 01 of your Java learning journey.");
+        
+        // Print without moving to next line
+        System.out.print("Java is ");
+        System.out.print("awesome!");
+        System.out.println(); // Move to next line
+        
+        // Print with formatting
+        System.out.println("Let's learn Java together!");
+    }
+} 

Day 01 - Java Basics and Setup/README.md

@@ -0,0 +1,60 @@
+# Day 01 - Java Basics and Setup
+
+## 📚 What You'll Learn Today
+
+- Understanding what Java is and its history
+- Setting up your Java development environment
+- Writing your first Java program
+- Understanding the basic structure of a Java program
+- Running Java programs from command line
+
+## 🎯 Key Concepts
+
+### What is Java?
+Java is a high-level, object-oriented programming language that runs on billions of devices. It's known for its "Write Once, Run Anywhere" capability.
+
+### Java Program Structure
+Every Java program has these essential components:
+- **Class declaration**: `public class ClassName`
+- **Main method**: Entry point of the program
+- **Statements**: Instructions that perform actions
+
+### Basic Syntax Rules
+- Java is case-sensitive
+- Statements end with semicolons (;)
+- Code blocks are enclosed in curly braces {}
+- File name must match the public class name
+
+## 📁 Files in This Day
+
+1. **HelloWorld.java** - Your first Java program
+2. **BasicStructure.java** - Understanding Java program structure
+3. **Comments.java** - Different types of comments in Java
+
+## 🚀 How to Run
+
+1. Open command prompt/terminal
+2. Navigate to this folder
+3. Compile: `javac HelloWorld.java`
+4. Run: `java HelloWorld`
+
+## 💡 Exercises
+
+1. Modify the HelloWorld program to print your name
+2. Create a program that prints multiple lines
+3. Experiment with different comment types
+
+## 🔍 Common Issues
+
+- **'javac' is not recognized**: Make sure Java is installed and PATH is set
+- **File not found**: Ensure you're in the correct directory
+- **Compilation errors**: Check for typos and missing semicolons
+
+## 📖 Additional Resources
+
+- [Oracle Java Documentation](https://docs.oracle.com/javase/)
+- [Java Tutorial](https://docs.oracle.com/javase/tutorial/)
+
+---
+
+**Next Day**: Day 02 - Variables and Data Types