Java Reference
In-Depth Information
Java has a class
Long
(note the upper case L in
Long
), which defines two constants to represent maximum and
minimum values of
long
data type, L
ong.MAX_VALUE
and
Long.MIN_VALUE
.
long max = Long.MAX_VALUE;
long min = Long.MIN_VALUE;
The byte Data Type
The
byte
data type is an 8-bit signed Java primitive integer data type. Its range is -128 to 127 (-2
7
to 2
7
- 1). This is the
smallest integer data type available in Java. Generally,
byte
variables are used when a program uses a large number
of variables whose values fall in the range -128 to 127 or when dealing with binary data in a file or over the network.
Unlike
int
and
long
literals, there are no
byte
literals. However, you can assign any
int
literal that falls in the range of
byte
to a
byte
variable. For example,
byte b1 = 125;
byte b2 = -11;
If you assign an
int
literal to a
byte
variable and the value is outside the range of the
byte
data type, Java
generates a compiler error. The following piece of code will produce a compiler error:
// An error. 150 is an int literal outside -128 to 127
byte b3 = 150;
Note that you can only assign an
int
literal between -128 and 127 to a
byte
variable. However, this does not imply
that you can also assign the value stored in an
int
variable, which is in the range of -128 to 127, to a
byte
variable. The
following piece of code will generate a compiler error, because it assigns the value of an
int
variable,
num1
, to a
byte
variable,
b1
:
int num1 = 15;
// OK. Assignment of int literal (-128 to 127) to byte.
byte b1 = 15;
// A compile-time error. Even though num1 has a value of 15, which is in the range -128 and 127.
b1 = num1;
Java does not allow you to assign the value of a variable of a higher range data type to the variable of a lower range
data type because there is a possible loss of precision in making such an assignment. To make such an assignment
from
int
to
byte
, you must use a cast, as you did in the case of the
long
-to-
int
assignment. The assignment of
num1
to
b1
can be rewritten as follows:
b1 = (byte)num1; // Ok
After this cast from
int
to
byte
, the Java compiler would not complain about the
int
-to-
byte
assignment. If
num1
holds a value that cannot be correctly represented in the 8-bit
byte
variable
b1
, the higher order bits (9
th
to
32
nd
) of
num1
are ignored and the value represented in the lower 8 bits is assigned
b1
. In such a case of
int
-to-
byte
assignment, the value assigned to the destination
byte
variable may not be the same as the value of the source
int
variable if the value of the source variable falls outside the range of
byte
data type.
