Java wrapper classes

                                    ArrayList<Integer> myNumbers = new ArrayList<Integer>(); // Valid

                                    ArrayList<int> myNumbers = new ArrayList<int>(); // Invalid

                                    In Java, for each Primitive type, there is a matching class type.
  We call them Wrapper classes:
	Primitive types are the most basic data types
    available within the Java language. 
	There are 8: boolean , byte , char , short ,
                  int , long , float and double . 
	These types serve as the building blocks of
    data manipulation in Java.
	Wrapper classes: Byte, Short, Integer, Long,
                 Float, Double, Boolean, Character
			
	All the wrapper classes are subclasses
    of the abstract class Number. 
	The object of the wrapper class contains or
      wraps its respective primitive data type. 
	Converting primitive data types into object
    is called boxing, and this is taken care by the compiler.
			
			Differences: 
				1. Wrappers classes are object 
				2. null can only be assigned to classes
				3. Wrapper class does have methods
				4. Primitives does have default values
						default value of primitives:  
								 byte, short, int, long ==> 0
								 float, double ==> 0.0;
								 boolean ==> false;
								 char ==> space		 
				5. Default values of wrapper class: null