Name: 
Own Classes Simple Objects, Constructors & Overloading 
Hello 4 - Essential Knowledge & Learning Objectives
LEARNING OBJECTIVE		
Create objects by calling constructors with parameters.		
Identify, using its signature, the correct constructor being called. 		
Define instance variables for the attributes to be initialized through the constructors of a class.		
Call non-static void methods with parameters.		

ESSENTIAL KNOWLEDGE		
A method signature for a method with parameters consists of the method name and the ordered list of parameter types. 		
Methods are said to be overloaded when there are multiple methods with the same name but a different signature.		
The keyword null is a special value used to indicate that a reference is not associated with any object.		
The memory associated with a variable of a reference type holds an object reference value or, if there is no object, null. This value is the memory address of the referenced object.		
Using a null reference to call a method or access an instance variable causes a NullPointerException  to be thrown.