That we can use objects as instance variables (String is an object). This is called Composition. If we think of an object as a machine, the instance variables represent the gears. We don’t want to expose the gears to the user of the machine.
An object-oriented system can be characterized as a system of cooperating objects. Some objects interact only with certain other objects or perhaps only with a certain set of objects.
Everything in an object. A program is a set of objects telling each other what to do by sending messages. Each object has its own memory (made up by other objects). Every object has a type. All objects of a specific type can receive the same messages.
What is ObjectOrientedProgramming A class is the blueprint or template for its objects. Described through Name, Attributes and Methods. Objects are instances of a class. Each object has state, behavior and identity. You send messages to an object by making method calls
Objectorientedprogramming is not bound to a specific programming language; some require less code to be written; the important part is sticking to the established conventions
Classes are syntactic units used to define objects. They may contain instance variables, which will occur in each instance of the class, instance methods, which can be executed by objects of the class, and constructors, which are called automatically when an object is created using new.
OOP makes it easier to solve real-world problems by modeling natural objects in software objects. The OO thought process is more intuitive than procedural, especially for tackling complex problems.
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7.1 Introduction This chapter describes object-oriented computing and its use in data abstraction, particularly as it is understood in the Java language, including various forms of inheritance. The late 1980's saw a major paradigm shift in the computing industry toward "object-orientedprogramming".
