What Are Data Types in Java?

Data types define the kind of data a variable can hold — for example, a number, a character, or text.

Java’s Main Data Types

1️⃣ Primitive Data Types

Primitive data types are built-in, lightweight, and directly store their values in memory.

integer (integer number):

byte (8-bit; range -128 to 127)

byte b = 100;

short (16-bit; range -32,768 to 32,767)

short s = 1000;

int (32-bit; range -2,147,483,648 to 2,147,483,647)

int number = 50000;

long (64-bit; range much larger)

long large = 10000000000L;

floating point (Decimal number):

float (32-bit; less precision)

float f = 19.99f;

double (64-bit; greater precision)

double d = 19.99;

character:

char (16-bit Unicode character)

char grade = 'A';

boolean:

Stores true or false

boolean isJavaFun = true;

2️⃣ Reference (Non-Primitive) Data Types

Reference data types hold a reference to an object or array.

String:

String message = "Hello, Java!";

Array:

int[] numbers = {1, 2, 3, 4, 5};

String[] names = {"Alice", "Bob"};

Class and Object:

public class Person {
    String name = "Alice";

    void showName(){
        System.out.println(this.name);
    }
}

Person p = new Person();
p.showName();

Summary

• Primitive — Stores raw values directly (integer, float, boolean...).
• Reference — Stores a reference or pointer to an object (String, array, custom class...).