Java Data Types | Primitive Data Type | Reference Data Type
1) Primitive Data Types
2) Reference/Object Data
Types
What is Primitive Data
Types:
There are (8) primitive data types
supported by Java. Primitive data types are predefined by the language and
named by a keyword. Let us now look into detail about the eight primitive data
types.
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 4 times smaller than an int.
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)
Short data type can also be used to save memory
as byte data type. A short is 2 times smaller than an int
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)
Int 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, int 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
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 1 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: false.
Example: boolean one = true
char
char data type is a single 16-bit Unicode
character.
Minimum value: '\u0000' (or 0).
Maximum value: '\uffff' (or 65,535 inclusive).
Char data type is used to store any character.
Example: char letterA ='A'
What is Reference Data
Types:
- 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, Students, Dogs etc.
- Class objects, and various type
of array variables come under reference data type.
- Default value of any reference
variable is null.
- A reference variable can be
used to refer to any object of the declared type or any compatible type.
·
Example: Animal animal = new Animal("giraffe");
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