Java Variables — Free Java Tutorial

TL;DR: Learn Java Variables in Java with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

Java Variables in Java

Java is a statically-typed language — every variable must have a declared type. Java has two categories of data types: primitive types and reference types.

Primitive types store actual values directly in memory. There are 8 primitive types: byte, short, int, long, float, double, boolean, and char.

Reference types store a reference (memory address) to an object. Strings, arrays, and all class instances are reference types.

The most commonly used primitives are: `int` (whole numbers), `double` (decimal numbers), `boolean` (true/false), and `char` (single character).

Java also provides wrapper classes (Integer, Double, Boolean, Character) for every primitive — these are objects and provide useful utility methods.

Type casting allows you to convert between types. Widening (int → double) happens automatically; narrowing (double → int) requires explicit cast with `(type)`.

// Primitive types
int myInt = 10;
double myDouble = 9.99;
boolean myBool = true;
char myChar = 'A';
long myLong = 15000000000L;
float myFloat = 5.75f;

// Reference type
String myString = "Hello";

// Type casting
double d = 9.7;
int i = (int) d;  // narrowing: i = 9 (truncated)

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