Variables and Basic DataTypes

Although Java is object oriented, not all types are object. There are primitive types as well. Here is a list of all primitive types in Java:

Primitive Datatypes:

Data Type	Description	Size	Example Literals	Range
byte	twos complement integer	8 bits	(none)	-2^7…2^7-1
short	twos complement integer	16 bits	(none)	-2^15…2^15-1
int	twos complement integer	32 bits	-2, -1, 0, 1, 2	-2^31…2^31-1
long	twos complement integer	64 bits	-2L, -1L, 0L, 1L, 2L	-2^63…2^63-1
float	IEEE 754 floating point	32 bits	1.23e100f, -1.23e-100f, .3f, 3.14F
double	IEEE 754 floating point	64 bits	1.23456e300d, -1.23456e-300d, 1e1d
boolean	true or false	1 bit	true, false	0…1
char	Unicode character	16 bits	‘a’, ‘\u0041’, ‘\101’, ‘\’, ‘'’, ‘\n’, ‘ß’	‘\u0000’…‘\uffff’ or 0…65,535 inclusive

Reference Datatypes:

Data Type	Description	Size	Example Literals	Range
Class objects and various type of array variables	These variables are declared to be of a specific type that cannot be changed	-	Animal animal = new Animal(giraffe);	-

Numbers

byte a = 68;
int myNumber = 5;
double d = 4.5;
float f = (float) 4.5;
float f = 4.5f; // (f is a shorter way of casting float)

Characters and Strings

char c = 'g';

Double quotes automatically creates a new String object. String objects are immutable, which means that once created, their values cannot be changed.
For example: String s = "this is a string";

String s1 = new String("Who let the dogs out?"); // String object stored in heap memory
String s2 = "Who who who who!";	// String literal stored in String pool

Boolean

boolean b = false;

Hope to see you in the next article…