8 Primitive Data Types in Java with Sizes

Direct Answer

Java has eight primitive types: byte (8-bit), short (16-bit), int (32-bit), long (64-bit), float (32-bit IEEE 754), double (64-bit IEEE 754), char (16-bit UTF-16 code unit), and boolean (true or false; its storage size is not specified by the Java language). Primitive values are not objects and cannot be null.

Code Example

public class PrimitivesDemo {
    public static void main(String[] args) {
        byte age = 25;                // small whole number
        short year = 2024;            // medium whole number
        int score = 95;               // default integer
        long userId = 9876543210L;    // large number — needs L
        float rating = 4.5f;          // decimal — needs f
        double price = 9.99;          // default decimal
        char grade = 'A';             // single character, 2 bytes
        boolean isPassed = true;      // true or false only

        System.out.println("Score: " + score + ", Grade: " + grade);
        System.out.println("User " + userId + " paid " + price);
    }
}
// Output:
// Score: 95, Grade: A
// User 9876543210 paid 9.99

Every variable here is a primitive — no new keyword, no objects, just values stored directly.

Common Mistakes & Pitfalls

• Thinking char is 1 byte like in C: Java's char is 2 bytes because it stores a UTF-16 Unicode code unit, not an ASCII byte — anyone coming from C or C++ gets this wrong.
• Mixing up float and double: float is 4 bytes (~7 significant digits), double is 8 bytes (~15). Reaching for float to "save space" on a single value buys nothing and quietly loses precision — double is the default for a reason.
• Forgetting the literal suffix: long big = 10000000000; does not compile — the literal is read as an int and overflows. Write 10000000000L. Same trap with float f = 3.14;, which needs 3.14f.
• Assuming a primitive can be null: int x = null; is a compile error. Primitives always hold a value — switch to the wrapper (Integer, Double) only when "absent" is a state you genuinely need to represent.