Introduction :
Datatypes defines the type of data
that a variable can store .
Based on the data type of a
variable, the operating system allocates memory and decides what can be stored
in the reserved memory. Therefore, by assigning different data types to
variables, we can store integers, decimals, or characters in these variables.
About Datatypes :
Datatype is a spacial keyword used to
allocate sufficient memory space for the data, in other words Data type is used
for representing the data in main memory (RAM) of the computer.
There are two types of data types
are available in Java −
1)Primitive
Data Types
Primitive Data Types :
Primitive datatypes are the datatypes those are already defined in java.
These are eight in numbers . Primitive datatypes are predefined by the
language and named by a keyword.
These are – byte , short , int ,
long , float , double , Character , boolean
byte
-
Byte data type is an 8-bit signed two's complement
integer
-
Minimum value is -128( i.e.- 2^7)
-
Maximum value is 127 (i.e. 2^7-1)
-
Default value is 0
-
It is used to
save space in large java/j2ee
classes bangalore arrays, mainly
in place of integers, since a byte is four times smaller than an integer.
-
Example: byte x
= 101 , byte y = -54
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 (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 integer
-
Default value is 0.
-
Example: short
x = 10000, short y = -20000
int :
-
Minimum value is - 2,147,483,648 (-2^31)
-
Maximum value is 2,147,483,647 (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 x
= 100000, int y = -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 (2^63 -1)
-
This type is used when a wider range than int is
needed
-
Default value is 0L
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 best
core java training in bangalore never be used for precise values such as
currency
-
Default value is 0.0d
-Example: double x = 121.9
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 letterA = 'A'
Reference Datatypes/Nonprimitive datatype
:
-
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, Student , etc.
-
Class objects and various type of array variables come
under reference datatype.
-
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: Employee emp = new Employee(“abc”);
Some Important points :
-
The size of data types remain the same on all
platforms (standardized)
-
char data type in Java is 2 bytes because it
uses UNICODE character set. By virtue of it , Java supports
internationalization. UNICODE is a character set which covers all known scripts
and language in the world.
This is the short description
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