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Tutorial on Java classes and objects

 Java Classes and Objects:

Classes and objects both are treated in similar way in all programming languages. Java is not exception.

Understanding classes and objects with real world example

Consider a physical class room with lot of real world objects. What we Observe in class room..?

• Chairs 
• Table
•  Students
•  Teacher
•  Black board
• Markers and Erasers etc

So, a programmer needs to instruct the computer, how to create a class room object and it's subsequent objects. like, chair, table, teacher and student etc.

If programmer wants to create or develop a School application, he would need to create:

• class room object
• Office room object,
• Student object,
• Stationary object
• Play room object etc

Let us now create School application with above mentioned objects and classes using java programming language.

To create Objects, first of all, we have to create respective classes in java

public class School_Application{

     public Student students;

     public Teacher teachers;

     public ClassRoom classRoom;

      public School_Application(Student students, Teacher teachers, ClassRoom classRoom){

          this.students = students; 

          this.teachers = teachers; 

          this.classRoom = classRoom;

   }

}

Subsequently, programmer needs to create, Student, Teacher and ClassRoom classes and respective objects in main() method.

Objects in java are created using new operator. Example:

School_Application app = new School_Application(student, teachers, classRoom);

Happy coding! :)

Tutorial on coding and best practices

 Write code or write code in right way...

Writing a coding solution to a problem can be done in many ways. If the solution can be obtained with less number of code lines, then it is easy to understand and maintain.

But what if code is large with having millions of lines. Moreover maintenance and readability becomes difficult as the code base grows... Right? 

In this blog I want to share my views and experiences on writing code efficiently and effectively with less maintenance efforts.

Aspects to consider while coding:

• Naming convention
• Cyclomatic Complexity
• SOLID principles
• DRY Principle
• Managing dead code
• Comments

Naming conventions:

Every programming language mandates few norms in order to name variables, classes and functions etc. For ex: Java uses class names first letter to be a upper case and rest to be lower case letters. 

But if we dig little bit more, naming conventions are not limited to only upper case or lower case letters and using alphanumeric letters etc.

Naming a variable must be enough concise as naming your first child's name...

Few bad names for variables and constants:

          int final static TWO = 2;  [wrong]

          int final static MAX_LENGHT = 2; [Correct] 

  

Cyclomatic Complexity:

Cyclomatic complexity is a measure or metric to estimate complexity level of a snippet or block of code. 

Cyclomatic complexity and best practices:

• Never put more than three conditional checks (&& operator and || operator etc.) in one if condition
• Never exceed more than thirty lines in one function or method.
• Never exceed more than 1000 lines in one class or one file.

SOLID principles:

Usually developing a large and scalable application, requires better design. Adhering to SOLID principles yields better scalable and easily maintainable applications.

There are five SOLID principles. They are:

1. Single Responsibility Principle
2. Open/Closed Principle
3. Liskov's Substitution Principle
4. Interface Segregation Principle
5. Dependency Inversion Principle

DRY Principle:  

DRY stands for Do Not Repeat Yourself. Sometimes, There could be a need to use same or similar set of lines of code to be used multiple times in the same application. For ex. String utilities, DB connections or updating records in database etc.

Writing frequently used code snippets multiple times is not a good practice. Instead move this code to a function or method and use this method in places where ever required.

Simple use cases are:

• DB Connections
• File IO Operations
• String Utilities etc. 

Managing Dead Code:

Sometimes there are some lines or instructions in code base, which are completely not executed in all cases at all. This is considered as dead code. 

Dead code reduces the quality with respect to the readability.  

Comments:

Comments increases the readability of the program for programmers. Comments are written at class level, method level and variable level [Constants, instance variables and class variables] differently. 

The reason for this difference is, the pattern of comments is identified by API document generator tools and generates API documents.

Conclusion:

What all I tried to share through this post is, writing code for a specific problem can be done in different ways. But making sure that the program is more readable, maintenance free and easily scalable is also very important. 

The above few solutions or hacks will definitely help in developing better applications. 

Hope you enjoyed reading the post. Comments are welcomed. Thank you!! 

Happy coding!..