Java Reference
In-Depth Information
name,optionallyfollowedbyasequenceofsquarebracketpairs,andterminatedwitha
semicolon character (
;
). Consider the following examples:
int counter;
double temperature;
String firstName;
int[] ages;
char gradeLetters[];
float[][] matrix;
Thefirstexampledeclaresanintegervariablenamed
counter
,thesecondexample
declares a double precision floating-point variable named
temperature
, the third
example declares a string variable named
firstName
, the fourth example declares
a one-dimensional integer array variable named
ages
, the fifth example declares a
one-dimensional character array variable named
gradeLetters
, and the sixth ex-
ample declares a two-dimensional floating-point array variable named
matrix
. No
stringisyetassociatedwith
firstName
,andnoarraysareyetassociatedwith
ages
,
gradeLetters
, and
matrix
.
Caution
Squarebracketscanappearafterthetypenameorafterthevariablename,
but not in both places. For example, the compiler reports an error when it encounters
int[] x[];
.Itiscommonpracticetoplacethesquarebracketsafterthetypename
(asin
int[] ages;
)insteadofafterthevariablename(asin
char gradeLet-
ters[];
).
You can declare multiple variables on one line by separating each variable from its
predecessor with a comma, as demonstrated by the following example:
int x, y[], z;
This example declares three variables named
x
,
y
, and
z
. Each variable shares the
sametype,whichhappenstobeinteger.Unlike
x
and
z
,whichstoresingleintegerval-
ues,
y[]
signifiesaone-dimensionalarraywhoseelementtypeisinteger-eachelement
stores an integer value. No array is yet associated with
y
.
Thesquarebracketsmustappearafterthevariablenamewhenthearrayisdeclaredon
thesamelineastheothervariables.Ifyouplacethesquarebracketsbeforethevariable
name,asin
int x, []y, z;
,thecompilerreportsanerror.Ifyouplacethesquare
bracketsafterthetypename,asin
int[] x, y, z;
,allthreevariablessignifyone-
dimensional arrays of integers.
