Data Type in Java

Java is a strongly typed language. Hence every element to be declared, must strictly define its type.

Example:  

int x =10;
char c;

Here, x is a variable of the type ‘int’ which is initialized by a value of 10 and c is a variable of type ‘char’.

There are two kinds of data type in Java. They are,

1. Primitive data type
2. Reference type 

Details are :-

1. Primitive Data Type:

• Java defines 8 primitive data types – byte, short, int, long, float, double, char, Boolean.
• The primitive types byte, short, int, long – represents signed integer values.

byte:

• Description: Smallest integer type. Useful to work with raw binary data. E.g data from a network or file.
• Size (in Byte): 1
• Range: -128 to 127
• Example: byte b=5;

short:

• Description: 16 bit signed integer type. Least used.
• Size (in Byte): 2
• Range: -32,768 to 32,767
• Example: short num=5;

int:

• Description: Signed 32 bit type. Commonly used in expressions which requires a larger range; also to control loops, index arrays.
• Size (in Byte): 4
• Range: -2,147,483,648 to 2,147,483,647
• Example: int i=567;

long:

• Description: Signed 64 bit type and used when ‘int’ is not enough to hold the value.
• Size (in Byte): 8
• Range: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
• Example: long num=2233720368;

float:

• Description: Real numbers. Decimal with a single precision.
• Size (in Byte): 4
• Range: 1.4e–045 to 3.4e+038
• Example: float temp=52.5;

double:

• Description: Decimal with double precision. Math functions like sin(), cos() and sqrt() return double values.
• Size (in Byte): 8
• Range: 4.9e–324 to 1.8e+308
• Example: double sal= 0.50;

char:

• Description: Data type to store characters. Unicode values are used to store characters.
• Size (in Byte): 2
• Range: 0 to 65,536
• Example: char ch = ‘d’;

boolean:

• Description: Data type to store logical value i.e. true or false. This type is returned by all relational operators and required by conditional expressions like ‘if’ and ‘for’.
• Stores either “true” or “false”
• Example: boolean flag=true;

2. Reference Type:

• A reference type is a data type that refers to an object in memory. They can be instantiated.
• Reference type does not store the actual value, but stores the address. References are of type class, interface and array.

Example:

String st = new String(); // st is a reference variable of reference type ‘String’
Bird b1;