Object-oriented programming with Java

Object-oriented programming with Java
Ahmed Al-Ajeli
Lecture1
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Course Contents
•Introduction to object-oriented programming…
•…with a strong software engineering foundation…
•…aimed at producing and maintaining large, high-quality software systems.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Buzzwords
interface
overloading
encapsulation
coupling
cohesion
polymorphism
inheritance
mutator methods
collection classes
overriding
iterators
information hiding
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Goals
•Sound knowledge of programming principles
•Sound knowledge of object-orientation
•Able to critically assess the quality of a (small) software system
•Able to implement a small software system in Java
Object-oriented programming with Java
Ahmed Al-Ajeli
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Book
David J. Barnes & Michael K?lling Objects First with Java A Practical Introduction using BlueJ 5th edition,
Pearson Education, 2012
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Course overview (1)
•Objects and classes
•Understanding class definitions
•Object interaction
•Grouping objects
•More sophisticated behaviour – libraries
•Designing classes
Object-oriented programming with Java
Ahmed Al-Ajeli
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Course overview (2)
•Well-behaved objects - testing, maintaining, debugging
•Inheritance
•Polymorphism
•Extendable, flexible class structures
•Building graphical user interfaces (GUI)
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Object-oriented programming (1)
•OOP is a method of programming in which programs are made up of cooperating objects.
•philosophy: modularity and reuse apply to data as well as functions; when solving a problem, must identify the objects involved, e.g. banking system: customer, checking account, savings account, …
Object-oriented programming with Java
Ahmed Al-Ajeli
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Object-oriented programming (2)
•develop a software model of the objects in the form of abstract data types (ADTs).
•an ADT is a collection of data items and the associated operations on that data.
•In Java, ADTs are known as classes.
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Procedure-oriented vs object-oriented programming
•In POP, the primary focus is on functions,
i.e. How; data and functions are separate
entities
•In OOP, the focus is on the data, i.e. What;
data and functions are treated as an
integrated entity.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Classes and objects
•Fundamental to much of the early parts of this course.
•Class: category or type of „thing?. Like a template or blueprint.
•Object: belongs to a particular class and has individual characteristics.
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Fundamental concepts
•object
•class
•method
•parameter
•data type
It is vital to understand these concepts as soon as possible.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Classes and Objects
•A class
–represents all similar objects of a kind (example: “car”)
•objects
–represent „things? from the real world, or from some problem domain;
–example: “that red car in the parking lot”.
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Methods and Parameters
•Objects have operations which can be invoked (Java calls them methods).
•Methods may have parameters to pass additional information needed to execute
–Parameters introduce variation into the effect of method calls.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Other observations
•Many distinct instances can be created from a single class.
•An object has attributes: values stored in fields.
•The class defines what fields an object has, but each object stores its own set of values (the state of the object).
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Source code
•Each class has source code associated with it that defines its details (attributes and methods).
•The source code is written to obey the rules of a particular programming language.
•We will explore this in detail in the next chapter.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Return values
•Some methods have void return types; but …
•… methods may return a result via a return value.
•Such methods have a non-void return type.
•More on this in the next chapter.
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Key elements of OOP (1)
•Data abstraction: an abstraction (class) focuses on the outside view of an object and separates its essential behaviour form the internal implementation details
•Encapsulation (or information hiding): it is the result of hiding the internal implementation details of an abstraction. It separates interface from implementation.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Key elements of OOP (2)
•Inheritance: is one of the most powerful paradigms of OOP, where new classes are derived from existing ones.
•Q- When can a language be an OO language?
A- when it provides direct and easy tools
for the key elements of OOP (Data
abstraction – encapsulation - inheritance).
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Java
•an OO language created by James Gosling.
•becoming widely used for
teaching programming.
•also, becoming very
important commercially.
•Java itself provides very clean implementation of OOP concepts.
Object-oriented programming with Java
Ahmed Al-Ajeli
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Getting started
•We will be using Java (compiler) & Eclipse (IDE)
•can be downloaded for free from the Web
•Java (JDK11) from www.oracle.com
•Eclipse (SimRel 2018-09) from
www.eclipse.org
•be sure to download & install Java first, then Eclipse