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
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:
Even though there are many numeric types in Java, the most used for numbers
int (for whole numbers) and
double (for floating point numbers). However, we will describe them all as you continue to
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:
byte myNum = 100; System.out.println(myNum);
short data type can store whole numbers from -32768 to 32767:
short myNum = 5000; System.out.println(myNum);
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.
int myNum = 100000; System.out.println(myNum);
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":
long myNum = 15000000000L; System.out.println(myNum);
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.
double data types can store fractional numbers. Note that you should end the value with an "f" for floats and "d" for doubles:
float myNum = 5.75f; System.out.println(myNum);
double myNum = 19.99d; System.out.println(myNum);
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 15 digits. Therefore it is safer to use
double for most calculations.
A floating point number can also be a scientific number with an "e" to indicate the power of 10:
float f1 = 35e3f; double d1 = 12E4d; System.out.println(f1); System.out.println(d1);