03 Java Fundamentals

Variables and Data Types in Java

By Dummy for Dummies

Variables

Monkey loves bananas. Monkey collects bananas. But Monkey can only carry so many at once. To hold more, Monkey needs pockets or bags. Find a bag, and every banana goes inside it.

But bananas aren't the only thing Monkey likes. Monkey also likes mangoes and apples. So Monkey finds two more bags, one per fruit, each with its own section to keep things sorted.

Why bother with bags at all? Small numbers like 2 + 2 are easy to type. But sometimes you're dealing with something like this:

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:

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

Common Data Types in Java

Points 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
• Variable names must start with a small letter and can only contain letters, numbers, or underscore _
• Each line of code in Java ends with a semicolon ;

Creating Variable Inside Code

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

1. It is a word so Datatype will be String
2. Name can be anything but must start with a small letter
3. Use equality = to assign the value
4. Then write the value "Skibidi"
5. After end of each line of code in java write semi colon ;

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

Extra Tips

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).