type wrapper or wrapper class object encapsulates or wraps primitive types. These classes are used to represent primitive values in OO fashion. Sometimes we need to represent the primitive values as objects, and then we have to go for wrapper classes.
Int---Integer
Short---Short
Byte---Byte
Long---Long
Float---Float
Double---Double
Char---Character
Boolean---Boolean
--to convert primitive values to wrapper type, we use the constructors of wrapper classes.
--to convert wrapper objects to primitive value, we use the xxxValue().
--if we want to use the object of one class in other class, we have to declare that class as an instance variable in the using class.
