Data Types and keywords in Java

What is a Data Type?

Data type is used to specify the type and their size of data,different languages have different sizes fo the different data types

The data types of Java are classified into two types

1. Primitive Data type
2. Non-Primitive Data type

### Primitive Data type

Integer type data types

Type	size in bytes	range	Default value	example
int	4	–2,147,483,648 to 2,147,483,647	0	int i=32
short	2	–32,768 to 32,767	0	short s=11
long	8	–9,223,372,036,854,775,808 to9,223,372,036,854,775,807	0	long l=24235345
byte	1	–128 to 127	0	byte b=13

float type data types

Type	size in bytes	range	Default value	example
float	4	±3.40282347E+38F	0.0f	float f=123.10f
double	8	±1.79769313486231570E	0.0d	double d=12.10

decimal numbers are always classified into double, if user doest use character f .if the user uses suffix f with the value, then it is a float datatype

• Q) Should i use suffix d in the value for double data type in java?

A) There is no difference ,you can use suffix d,or if you wont use the datatype is automatically taken as double

Characters datatype

Type	size in bytes	range	Default value	example
char	2	0 to 65535	\u0000 (0)	char c=’a’

For char type the input value should in singe quotes ,like in the example above the value for c is a ,and this character a is between singles quotes ‘a’

Boolean datatype

a boolean data type can be declared using the below syntax, and the value can be either true or false, and this data type cannot be converted into other data types

boolean b; // Declares a boolean variable named done

b = true; // Assigns true to done

Non-Primitive Data type

• Non-Primitive Data types are the data types which are called as refernce data types, beacuse they are used to refer objects
• Non-Primitive Data types are not predifined data types,they are user defined by the user ,(string is the only Non-prmitive datatype which is defined by java)
• These are used to refer the objects and they can be used to call methods ,from the class and perform some operations
• While prmitive data tyes have some value,Non prmitive datatype can be assigned with a null .
• Examples for Non-Primitive Data types are Strings, Classes, Arrays, Interface

Keywords in Java

Keywords are the reserved words which can be used to name any variable in the java program. these are predefine and have special meaning and does special task inside the program

abstract	assert	boolean	break	byte
case	catch	char	class	const
continue	default	do	double	else
enum	extends	final	finally	float
for	goto	if	implements	import
instanceof	int	interface	long	native
new	package	private	protected	public
return	short	static	strictfp	super
switch	synchronized	this	throw	throws
transient	try	void	volatile	while