Primitive java - Data Structures and Problem Solving Using Java - page 7

figure 1.2
The eight primitive
types in Java

Primitive Type What It Stores Range

byte

8-bit integer -128 to 127

short

16-bit integer -32,768 to 32,767

int

32-bit integer -2,147,483,648 to 2,147,483,647

-2 63 to 2 63 - 1

long

64-bit integer

6 significant digits ( 10 -46 , 10 38 )

float

32-bit floating-point

15 significant digits ( 10 -324 , 10 308 )

double

64-bit floating-point

char

Unicode character

boolean

Boolean variable false and true

languages. The low end of Unicode is identical to ASCII. The final primitive
type is boolean , which is either true or false .

1.3.2 constants

Integer constants can be represented in either decimal, octal, or hexadecimal nota-
tion. Octal notation is indicated by a leading 0 ; hexadecimal is indicated by a lead-
ing 0x or 0X . The following are all equivalent ways of representing the integer 37:
37 , 045 , 0x25 . Octal integers are not used in this text. However, we must be aware of
them so that we use leading 0 s only when we intend to. We use hexadecimals in
only one place (Section 12.1), and we will revisit them at that point.

Integer constants
can be repre-
sented in either
decimal , octal , or
hexadecimal
notation.

A character constant is enclosed with a pair of single quotation marks, as in
'a' . Internally, this character sequence is interpreted as a small number. The output
routines later interpret that small number as the corresponding character. A string
constant consists of a sequence of characters enclosed within double quotation
marks, as in "Hello" . There are some special sequences, known as escape sequences ,
that are used (for instance, how does one represent a single quotation mark?). In this
text we use '\n' , '\\' , '\'' , and '\"' , which mean, respectively, the newline charac-
ter, backslash character, single quotation mark, and double quotation mark.

A string constant
consists of a
sequence of char-
acters enclosed by
double quotes.

Escape sequences
are used to repre-
sent certain char-
acter constants.

1.3.3 declaration and initialization
of primitive types

Any variable, including those of a primitive type, is declared by providing its
name, its type, and optionally, its initial value. The name must be an identifier .
An identifier may consist of any combination of letters, digits, and the under-
score character; it may not start with a digit, however. Reserved words, such

A variable is named
by using an
identifier .