primitive : Java Glossary

2007-09-25 by Roedy Green ©1996-2008 Canadian Mind Products
Go to : punctuation 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z (all)

primitive

Primitive variables include boolean, char, byte, short, int, long, float and double. Strings, arrays and Objects are not considered primitives.

Java Primitives
Type	Signed?	Bits	Bytes	Digits	Lowest	Highest	Mnemonic
boolean	n/a	1	1	1	false	true	zero/one
char	unsigned Unicode	16	2	4:5	'\u0000' [0] aka Character.MIN_VALUE	'\uffff' [2¹⁶-1] aka Character.MAX_VALUE	Unicode chars are twice as big as C’s.
byte	signed	8	1	2:3	-128 [-2⁷] aka Byte.MIN_VALUE	+127 [2⁷-1]aka Byte.MAX_VALUE	Bytes are signed, so half the usual 255 range.
short	signed	16	2	4:5	-32,768 [-2¹⁵] aka Short.MIN_VALUE	+32,767 [2¹⁵-1] aka Short.MAX_VALUE	32K
int	signed	32	4	9:10	-2,147,483,648 [-2³¹] aka Integer.MIN_VALUE	+2,147,483,647 [2³¹-1] aka Integer.MAX_VALUE	2 gig
long	signed	64	8	18:19	-9,223,372,036,854,775,808 [-2⁶³] aka Long.MIN_VALUE	+9,223,372,036,854,775,807 [2⁶³-1] aka Long.MAX_VALUE	9 exabytes, or 9 billion gig
float	signed exponent and mantissa	32	4	6:7	±1.40129846432481707e-45 aka Float.MIN_VALUE	±3.40282346638528860e+38 aka Float.MAX_VALUE or roughly ±2¹²⁷ with 6 to 7 significant digits of accuracy. A float can exactly represent integers in the range -2²⁴ to +2²⁴.	rough, compact float
double	signed exponent and mantissa	64	8	14:15	±4.94065645841246544e-324 aka Double.MIN_VALUE	±1.79769313486231570e+308 aka Double.MAX_VALUE or roughly ±2¹⁰²³ with 14 to 15 significant digits of accuracy. A double can exactly represent integers in the range -2⁵³ to +2⁵³.	high precision float

When do you use float and when double? It depends how much precision you need. Because modern floating point hardware is all built on double, normally the only time you use float is for float[] or for float fields in plentiful Objects to conserve space when you don’t need the precision.

Similarly you normally use int in preference to short, char or byte except in arrays or Object fields, even when you don’t need the extra range because modern computer hardware is based around 32-bit quantities.

binary formats
corner case
floating point
IEEE 754 Floating point format
int vs Integer: float vs Float etc
Java Cheat Sheet
literal
sizeof
unsigned

	Please email your feedback for publication, errors, omissions, broken/redirected link reports and suggestions to improve this page to Roedy Green :
	Canadian Mind Products
	mindprod.com IP:[65.110.21.43]
	Your face IP:[38.103.63.18]	The information on this page is for non-military use only.
	You are visitor number 19,612.	Military use includes use by defence contractors.
	You can get a fresh copy of this page from:	or possibly from your local J: drive (Java virtual drive/Mindprod website mirror)
	http://mindprod.com/jgloss/primitive.html	J:\mindprod\jgloss\primitive.html