What is Object?
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An Instance of a Class.
·
Think
of an object as a fancy variable.
·
It
stores data, but you can “make requests” to that object, asking it to perform
operations on itself.
·
To make a request of an object, you
“send a message” to that object.
·
An object can be considered a "thing" that
can perform a set of related activities.
The set of activities that the object performs defines the object's behavior.
For example, the hand can grip something or a Student (object)
can give the name or address.
·
Real-world
objects share two characteristics: They all have state and behavior.
Dogs have state (name, color, breed and hungry) and behavior (barking,
fetching, wagging tail). Bicycles also have state (current gear, current pedal
cadence, and current speed) and behavior (changing gear, changing pedal
cadence, applying brakes). Identifying the state and behavior for real-world
objects is a great way to begin thinking in terms of object-oriented
programming.
·
In order to clearly understand the object
orientation, let’s take your “hand” as
an example. The “hand” is
a class. Your body has two objects of type hand, named left hand and right
hand. Their main functions are controlled/ managed by a set of electrical
signals sent through your shoulders (through an interface). So the shoulder is
an interface which your body uses to interact with your hands. The hand is a
well architected class. The hand is being re-used to create the left hand and
the right hand by slightly changing the properties of it.
