OOPS in JAVA 23

OOPS in JAVA 23

Wrapper class in Java

Wrapper class in java provides the mechanism to convert primitive into object and object into primitive. 

Since J2SE 5.0, (auto)boxing and unboxing feature converts primitive into object and object into primitive automatically. The automatic conversion of primitive into object is known and (auto)boxing and vice-versa unboxing.

One of the eight classes of java.lang package are known as wrapper class in java. The list of eight wrapper classes are given below. 

boolean	Boolean
char	Character
byte	Byte
short	Short
int	Integer
long	Long
float	Float
double	Double

Example of boxing and unboxing:

public class Test{
public static void main(String args[]){
Integer x = 5; // boxes int to an Integer object
x = x + 10; // unboxes the Integer to a int
System.out.println(x);
}
}
Output:
15

When x is assigned integer value, the compiler boxes the integer because x is integer object. Later, x is unboxed so that they can be added as integer.