Language basics - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 34

Table 2.1 Java primitive data types.

Type Values Default Size Range

-128 to 127

byte signed integer 0 8-bit

-32768 to 32767

short signed integer 0 16-bit

-2147483648 to 2147483647

int signed integer 0 32-bit

-9223372036854775808 to
9223372036854775807

long signed integer 0 64-bit

- 1.4012985E-45 to
- 3.4028235E+38,
- infinity, - 0, NaN

float IEEE 754

floating-point

0.0 32-bit

- 4.9E-324 to
- 1.7976931348623157E+308,
- infinity, - 0, NaN

double IEEE 754

floating-point

0.0 64-bit

\ u0000 or 0 \ u0000 to \ uFFFF or

char Unicode character

or Unsigned integer

16-bit

0 to 65535

boolean true, false false 1 bit in 32

bit integer

Not applicable

The IEEE 754 floating-point standard is used for the 32-bit float and 64-bit
double types. We discuss floating-point in more detail later in Section 2.11 and
in Appendix 3.
Historically, standard characters were typically represented with the 7-bit
ASCII encoding. Various other 8-bit encoding schemes exist to provide an addi-
tional 128 characters for symbols or for the characters needed for particular
languages. To provide internationalization with a single encoding requires more
than the 256 characters available with 1 byte. The Java designers decided to
use the 2-byte character type encoding called the Unicode system for the char
type. (J2SE 5.0 adds support for an even larger 4-byte system known as Uni-
code 4.0.) The char type can also act as a 16-bit unsigned integer in some
cases. (See Section 9.7 for more about character encoding.)
The boolean (true/false) type provides for the many kinds of logical
operations carried out in almost any program. Though internally a boolean value
is eithera1or0integer, it cannot be used in arithmetic operations. (Represen-
tations of Boolean arrays are not specified for the JVM. Some implementations
use bit arrays.)
We discuss classes and objects later, but we note here that primitive types in
Java are not instances of classes. The decision to use simple data types broke
the symmetry and elegance of the language to some degree but vastly reduced
overhead and execution times compared to the case where all data types are
objects.