Primitive Data Types

ICS 111 with Blanca

The following table lists, by keyword, all of the primitive data types supported by Java, their sizes and formats, and a brief description of each. The MaxVariablesDemo program declares one variable of each primitive type.

Primitive Data Types

Keyword Description Size/Format
(integers)
byte Byte-length integer 8-bit two's complement
short Short integer 16-bit two's complement
int Integer 32-bit two's complement
long Long integer 64-bit two's complement
(real numbers)
float Single-precision floating point 32-bit IEEE 754
double Double-precision floating point 64-bit IEEE 754
(other types)
char A single character 16-bit Unicode character
boolean A boolean value (true or false) true or false

Purity Tip: In other languages, the format and size of primitive data types may depend on the platform on which a program is running. In contrast, the Java programming language specifies the size and format of its primitive data types. Hence, you don't have to worry about system-dependencies.

You can put a literal primitive value directly in your code. For example, if you need to assign the value 4 to an integer variable you can write this: 

int anInt = 4;
The digit 4 is a literal integer value. Here are some examples of literal values of various primitive types:

Examples of Literal Values and Their Data Types

Literal Data Type
178 int
8864L long
37.266 double
37.266D double
87.363F float
26.77e3 double
' c ' char
true boolean
false boolean

Generally speaking, a series of digits with no decimal point is typed as an integer. You can specify a long integer by putting an 'L' or 'l' after the number. 'L' is preferred as it cannot be confused with the digit '1'. A series of digits with a decimal point is of type double. You can specify a float by putting an 'f' or 'F' after the number. A literal character value is any single Unicode character between single quote marks. The two boolean literals are simply true and false.