Day 1: Java Basics – Why Am I Doing This to Myself?

So, I started learning Java today because apparently, printing "Hello, World!" is the first step toward greatness. I followed Kunal Kushwaha’s resources, and well… Java is already throwing new words at me. Here’s what I learned (and somehow survived).

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Programming Languages - Because One Doesn't Fit All

Turns out, there are different types of programming languages. Because why keep things simple?

1. Compiled Languages – These translate the whole code at once before running it. (Like turning in your homework and praying there are no mistakes.) Examples: C, C++.

2. Interpreted Languages – These read and run the code line by line (kind of like someone reading a book out loud). Examples: Python, JavaScript.

3. Java (Hybrid) – Java compiles first, then runs inside a Virtual Machine (JVM). Basically, Java doesn’t trust me to run code directly, so it checks everything first.

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Java Environments – Because Java Needs an Entire Toolbox

1. JDK (Java Development Kit)

This is everything I need to write and run Java programs. It includes:

• JRE (Java Runtime Environment) – So I can run Java programs.

• Java Compiler – Translates my code into something Java understands.

• Other Developer Tools – To help me debug, compile, and probably cry less.

2. JRE (Java Runtime Environment)

This is only needed to run Java programs, not write them. If all I want is to run Java apps (not code them), JRE is enough.

3. JVM (Java Virtual Machine)

The JVM is the real magician here. It runs Java code on any operating system by converting it into something my computer understands. That’s why Java is "Write Once, Run Anywhere" (or in my case, "Write Once, Debug Everywhere").

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Memory Management – Where My Variables Live

Java actually cares about where it stores stuff. Here’s how it works:

• Stack Memory – Quick, temporary storage for small stuff (like method calls and variables).

• Heap Memory – Stores objects and is managed by Garbage Collector (so I don’t have to clean up my own mess—nice).

In short, Java is smart enough to manage memory, but if I mess up, it will still remind me with an error message.

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Installing Java – Step 1 of the Struggle

Before I can even write code, I had to install JDK (Java Development Kit) from oracle.com or use OpenJDK.

To check if it worked, I ran this command:

java -version

If Java responded, great! If not, well… time to Google the problem (which I’m sure will happen a lot).

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Writing My First Java Program – The Famous "Hello, World!"

Here’s the first-ever Java program everyone writes:

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

Breaking It Down (Because Java Loves Fancy Words)

• public class Main – Creates a class (basically a container for my code).

• public static void main(String[] args) – This is the main method. Java won’t run without it.

• System.out.println("Hello, World!"); – Prints text to the screen (so I can pretend I did something important).

Ran it. It worked. I felt smart for five seconds.

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Taking Input & Output – Letting Users Type Stuff

Java is not a mind reader, so if I want input, I have to ask for it. Here’s how:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter your name: ");
        String name = sc.nextLine();
        System.out.println("Hello, " + name + "!");
    }
}

What’s Happening Here?

• import java.util.Scanner; – Brings in the Scanner (so Java knows how to take input).

• Scanner sc = new Scanner(System.in); – Creates a Scanner object (basically a keyboard listener).

• sc.nextLine(); – Reads what the user types.

Tried it. It worked. Now Java can actually interact with me instead of just printing stuff.

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Conditionals & Loops – Making Java Think

If-Else (Making Decisions)

I can tell Java to do different things based on conditions:

int age = 18;

if (age >= 18) {
    System.out.println("You can vote!");
} else {
    System.out.println("Too young, sorry.");
}

Java is now judging people based on their age. Cool.

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Loops (Making Java Repeat Stuff)

For Loop (Runs a Fixed Number of Times)

for (int i = 1; i <= 5; i++) {
    System.out.println("This is loop number " + i);
}

Java will run this five times. Good for repetitive tasks (or annoying people).

While Loop (Runs Until I Say Stop)

int x = 1;
while (x <= 5) {
    System.out.println("Still looping...");
    x++;
}

This loop runs as long as the condition is true. If I forget to update x, it never stops (which is how I accidentally crashed my code).

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What I Learned Today

• Java compiles and interprets code because it likes to be special.

• There are JDK, JRE, and JVM, and yes, I need to remember what they do.

• Memory is managed by Java’s Garbage Collector, so I don’t have to worry (until I do).

• I can finally print stuff, take input, and use loops without breaking everything (well, most of the time).

What’s Next?

Tomorrow, I’ll dive deeper into functions, arrays, and maybe recursion (if I’m brave enough). Stay tuned!

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