Data types in Java

There are two data types available in Java −

• Primitive Data Types
• Reference/Object Data Types

Primitive Data Types

There are eight primitive data types supported by Java. Primitive data types are predefined by the language and named by a keyword. Let us now look into the eight primitive data types in detail.

byte

• Byte data type is an 8-bit signed two's complement integer

• Minimum value is -128 (-2^7)

• Maximum value is 127 (inclusive)(2^7 -1)

• Default value is 0

• Byte data type is used to save space in large arrays, mainly in place of integers, since a byte is four times smaller than an integer.

• Example − byte a = 100, byte b = -50

short

• Short data type is a 16-bit signed two's complement integer

• Minimum value is -32,768 (-2^15)

• Maximum value is 32,767 (inclusive) (2^15 -1)

• The short data type can also be used to save memory as byte data type. A short is 2 times smaller than an integer

• The default value is 0.

• Example − short s = 10000, short r = -20000

int

• Int data type is a 32-bit signed two's complement integer.

• Minimum value is - 2,147,483,648 (-2^31)

• Maximum value is 2,147,483,647(inclusive) (2^31 -1)

• Integer is generally used as the default data type for integral values unless there is a concern about memory.

• The default value is 0

• Example − int a = 100000, int b = -200000

long

• Long data type is a 64-bit signed two's complement integer

• Minimum value is -9,223,372,036,854,775,808(-2^63)

• Maximum value is 9,223,372,036,854,775,807 (inclusive)(2^63 -1)

• This type is used when a wider range than int is needed

• Default value is 0L

• Example − long a = 100000L, long b = -200000L

float

• Float data type is a single-precision 32-bit IEEE 754 floating point

• Float is mainly used to save memory in large arrays of floating point numbers

• Default value is 0.0f

• Float data type is never used for precise values such as currency

• Example − float f1 = 234.5f

double

• The double data type is a double-precision 64-bit IEEE 754 floating point

• This data type is generally used as the default data type for decimal values, generally the default choice

• Double data type should never be used for precise values such as currency

• Default value is 0.0d

• Example − double d1 = 123.4

boolean

• boolean data type represents one bit of information

• There are only two possible values: true and false

• This data type is used for simple flags that track true/false conditions

• Default value is false

• Example − boolean one = true

char

• char data type is a single 16-bit Unicode character

• Minimum value is '\u0000' (or 0)

• Maximum value is '\uffff' (or 65,535 inclusive)

• Char data type is used to store any character

• Example − char letter A = 'A'

Reference Datatypes

• Reference variables are created using defined constructors of the classes. They are used to access objects. These variables are declared to be of a specific type that cannot be changed. For example, Employee, Puppy, etc.

• Class objects and various type of array variables come under reference data type.

• The default value of any reference variable is null.

• A reference variable can be used to refer any object of the declared type or any compatible type.

• Example − Animal animal = new Animal("giraffe");