03 Java Fundamentals | Variables and Data types in Java

VARIABLES

Monkey loves bananas. Monkey collects bananas. But monkey can collect and deal with only a limited number of bananas. To collect and utilize more bananas, Monkey needs pockets or bags. If Monkey finds a bag, it will put all the bananas inside.

But wait, bananas are not the only thing Monkey likes. Monkey also likes mangoes and apples. So Monkey finds 2 more bags. Now Monkey has each bag for each fruit. And each bag has different sections where it can put the fruits one by one.

Monkey = You (the programmer)
Fruits = Information (numbers, words, etc.)

Bags = Variables (where you store the info)

Now, why do you even need bags?
Because sometimes you deal with numbers like 2 + 2, easy stuff. But sometimes you’ll face a monster number like:

1234567890123456789

Imagine writing that everywhere in your code again and again. Painful, right?
Instead, you just give it a name like number or simply n .

Now, whenever you use n in your program, Java will treat it as 1234567890123456789. Easy, clean, and way more powerful when data grows big.

TYPES OF VARIABLES

Monkey was smart. Monkey put each fruit in a separate bag. You are smarter, you put each type of information in different variables as well. The different types or classes of variables are called "Data Types"

Consider you have 3 types of data/information:

an integer → 123
a decimal → 12.002

a word → "Coding"

Each type of data has its own class/type in Java:

123 → Integer (whole number)

12.002 → Double or Float (decimal numbers)

"Coding" → String (words, text)

In Java, there are many types of variables, and each specific type of data has a name according to its nature. Some important ones are:

Common Data Types in Java

int → Stores whole numbers, like 5 or -99 .
double → Stores decimal numbers, like 3.14159 .
float → Also for decimals, but less precise (used when memory matters).
char → Stores a single character, like 'A' or 'x' .
String → Stores text, like "Hello 123" .
boolean → Stores only true or false .
long → Stores very big whole numbers (Big int)
short → Stores smaller whole numbers (less memory).
byte → Even smaller whole numbers (used for efficiency).

THINGS TO REMEMBER

→ All datatype names are lower case except String, in which first letter is capital

→ String must be enclosed in double quotes like "Word"

→ char must be enclosed in single quote like 'A'

→ char can store just a single character 'L' or '@'

→ boolean values are both in lowercase i.e. true or false

CREATING VARIABLE INSIDE CODE

When creating a variable inside a code you need to first write it's datatype, then a name for it then assign it to a value. Let's store the word Skibidi in a variable.

It is a word so Datatype will be String
Name can be anything but.... must start with a small letter and must not contain characters other than _ (underscore)
Use equality = to assign the value
Then write the value "Skibidi"
After end of each line of code in java you write semi colon ;



 public class Main{
    public static void main(String[] args) {
        String name = "Skibidi";
        System.out.println(name); //This will print Skibidi
    }
}

OUTPUT:

Skibidi

CREATING ALL IN ONE CODE



 public class VariablesExample {
    public static void main(String[] args) {
        int bananas = 123;
        double price = 12.002;
        String hobby = "Coding";
        char grade = 'A';
        boolean isHappy = true;

        System.out.println(bananas); // This will print 123
        System.out.println(price); // This will print 12.002
        System.out.println(hobby); // This will print Coding
        System.out.println(grade); // This will print A
        System.out.println(isHappy); // This will print True
    }
}

OUTPUT:

123
12.002
Coding
A
true

EXTRA TIPS.

If you just create a variable and do not assign any value it is called "Decalaration"

int num;

When you assign it a valute later it is called initiation

num = 199;

CLOSING

That’s it for Variables and Data types!

In the next blog, Monkey won’t just store fruits, Monkey will start playing with them 🍌➕🍎 (yes, I’m talking about operations and expressions).

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03 Java Fundamentals | Variables and Data types in Java | By Dummy for Dummies

Common Data Types in Java