Java Numbers
Numbers
Primitive number types are divided into two groups:
Integer types stores whole numbers, positive or negative (such as 123 or -456), without decimals.
Valid types are byte
, short
, int
and long
. Which type you should use, depends on the numeric value.
Floating point types represents numbers with a fractional part,
containing one or more decimals. There are two types: float
and double
.
Even though there are many numeric types in Java, the most used for numbers
are int
(for whole numbers) and double
(for floating point numbers). However, we will describe them all as you continue to
read.
Integer Types
Byte
The byte
data type can store whole numbers
from -128 to 127. This can be used instead of int
or other integer types to
save memory when you are certain that the value will be within -128 and 127:
Short
The short
data type can store whole numbers from -32768 to 32767:
Int
The int
data type can store whole numbers from -2147483648 to 2147483647. In general, and in our tutorial, the int
data type is
the preferred data type when we create variables with a numeric value.
Long
The long
data type can store whole numbers from -9223372036854775808 to 9223372036854775807. This is used when int is not large enough to store the value. Note that you should end the value with an "L":
Floating Point Types
You should use a floating point type whenever you need a number with a decimal, such as 9.99 or 3.14515.
The float
and double
data types can store fractional numbers. Note that you should end the value with an "f" for floats and "d" for doubles:
Use float
or double
?
The precision of a floating point value indicates how many digits the value can have
after the decimal point.
The precision of float
is only six or seven
decimal digits, while double
variables have a
precision of about 16 digits. Therefore it is safer to use double
for most calculations.
Scientific Numbers
A floating point number can also be a scientific number with an "e" to indicate the power of 10:
Example
float f1 = 35e3f;
double d1 = 12E4d;
System.out.println(f1);
System.out.println(d1);