Variables

• Variables come in two flavors: primitive and reference
• Variable must always be declared with a name and a type.
• A primitive variable value is the bits representing the value (5, ‘a’,true, etc)
• A reference variable value is the bits representing a way to get to an object on the heap.
• A reference variable is like a remote control, using the dot operator (.) on a reference variable is like pressing a button on the remote control to a access a method or instance variable.
• A reference variable has a value of null when it is not referencing any object.
• An array is always an object, even if the array is declared to hold primitives.

Instance Variable Vs Local Variable.

Instance variable always gets a default value. these default values are

Data Type	Default Value
integers	0
floating points	0.0
booleans	false
references	null

• Instance variables are declared inside a class but not within a method.
• Local variables are declared within a method
• Local variables must be initialized before use

Equality of primitive or reference

• Two primitives can be compared using the == operator.
• When == is used for equality check of references it just tells if both reference point to the same Heap Address.