Java Video 19: Classes and Objects

In this video you will learn how to create, use and instantiate a Java class.

A class is a set of methods (aka subroutines, procedures, functions, behavior) and variables (aka properties, fields, instance fields, attributes, state) that are saved to a separate file in a way that they can be imported and reused by many programs. You can think of a class as a template or definition for an object. Nowadays, instead of writing programs that solve specific problems, some programmers (aka class developers) create classes (e.g. Google Maps) so that they can be reused by other programmers (aka client programmers) who have specific problems (e.g. find driving directions to a restaurant.) This phenomenom has led to an explosion of computer software. Games, apps, web applications, etc. are produced more easily, inexpensively and quickly because client programmers have access to classes that can be used in unrelated programmers. For example, a spell-checker class that was used by an old version of Microsoft Word could be reused in an app for a Windows smartphone. Or, a collision detection class that was used in a Mario program from the 1990's could be used in Angry Birds for a smartphone.

Usually, an individual Java project (i.e. program) uses many classes. Each class is stored and compiled in a separate file. The name of class is usually a noun and it must be the same as the name of its file.



Other videos:

Video1: How to Install NetBeans with JDK Cobundle.
https://www.youtube.com/watch?v=ctIiu...
Video2: First Java application:
https://youtu.be/GdelWG0ptcI
Video3: Java Variables:
https://www.youtube.com/watch?v=G2Gtp...
Video4: Java Arithmetic Operators
https://www.youtube.com/watch?v=zujQE...
Video5: Java Relational (comparison) Operators:
https://www.youtube.com/watch?v=W-l08...
Video6: Java Logical Operators:
https://www.youtube.com/watch?v=FK2_b...
Video7: Java Scanner How to Input Data Part1
https://youtu.be/fxKvL3z5id0
Video8: Java Scanner Part2 How to input from a text file and a web page
https://youtu.be/J2_ljyPJl9k
Video9: Java Methods :
https://youtu.be/fExBKROZORo
Video10: Java If statements :
https://youtu.be/PUc_aIwewGE
Video11: Java Switch case:
https://youtu.be/xywqQl8pVVA
Video12: Read and Write to a File:
https://youtu.be/UZZmJ8ylvcw
Video13: For loop:
https://youtu.be/J2PMZeE4-Wk
Video14: while loop:
https://youtu.be/Q6VO10S_KZw
Video15: do .... while loop:
https://youtu.be/YDxRHUdqiUM
Video 16 : One Dimensional Arrays:
https://youtu.be/cdwgBmZ8rNQ
Video 17 : Strings Part1:
https://youtu.be/-YuYSQ-7eQQ
Video 18 : Strings Part2 : Functions
https://youtu.be/KFwW1jtsltg
Java Video 19: Classes and Objects
https://youtu.be/2p2QU7nVvvE
Java Video 20: Inheritance | Abstract | Overloading | Overriding
https://youtu.be/xXt_KgTLrdA