Java Variables & Data Types

Primitive and reference types.

✍️ 2 exercises in this lesson

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Java is statically typed: every variable has a type: type name = value;

Primitive types

byte, short, int, long: whole numbers
float, double: decimals
boolean: true / false
char: a single character, in single quotes

Reference types include String, arrays and classes. final makes a variable a constant. var (Java 10+) lets the compiler infer the type.

Key Takeaways: Java Variables & Data Types

Mastering Java Variables & Data Types helps you write clean and reliable Java code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.

Java Variables & Data Types Code Example

Java

public class Main {
    public static void main(String[] args) {
        int age = 25;
        long population = 241_000_000L;
        double price = 2000.0;
        boolean active = true;
        char grade = 'A';
        String name = "Sara";
        final double TAX = 0.18;
        var city = "Lahore";

        System.out.println(name + " (" + age + ") from " + city);
        System.out.println("Grade " + grade + ", active: " + active);
        System.out.println("With tax: " + price * (1 + TAX));
        System.out.println("Population: " + population);
    }
}

Output

Sara (25) from Lahore
Grade A, active: true
With tax: 2360.0
Population: 241000000

Run this example on your own computer. The "Get Started" lesson shows how to set it up.

Java Variables & Data Types Practice Exercises

Check what you learned in “Java Variables & Data Types”.

/ 2 solved

Fill in the blank

Declare a whole-number variable.

 age = 25;

✓ Correct! Not quite. Try again.

Multiple choice

Which type holds a single character?

char String byte text

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Java Syntax & Output

Java Type Casting & Operators

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