Primitive wrapper class in Java

In object-oriented programming, a wrapper class is a class that encapsulates types, so that those types can be used to create object instances and methods in another class that needs those types. So a primitive wrapper class is a wrapper class that encapsulates, hides or wraps data types from the eight primitive data types,^[1] so that these can be used to create instantiated objects with methods in another class or in other classes.^[2][3] The primitive wrapper classes are found in the Java API.

Primitive wrapper classes are used to create an Object that needs to represent primitive types in Collection classes (i.e., in the Java API), in the java.util package and in the java.lang.reflect reflection package. Collection classes are Java API-defined classes that can store objects in a manner similar to how data structures like arrays store primitive data types like int, double, long or char, etc.,^[2] but arrays store primitive data types while collections actually store objects.

The primitive wrapper classes and their corresponding primitive types are:

Primitive type	Wrapper class	Constructor arguments
byte	Byte	byte or String
short	Short	short or String
int	Integer	int or String
long	Long	long or String
float	Float	float, double or String
double	Double	double or String
char	Character	char
boolean	Boolean	boolean or String