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.

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:

byte myNum = 100;
System.out.println(myNum);

Short

The short data type can store whole numbers from -32768 to 32767:

short myNum = 5000;
System.out.println(myNum);

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.

int myNum = 100000;
System.out.println(myNum);

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":

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.

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:

float myNum = 5.75f;
System.out.println(myNum);

double myNum = 19.99d;
System.out.println(myNum);

Scientific Numbers

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);