Lecture on Constants in Java

Outline

• Definition of Constants
• Ensuring a Constant Value
• Benefits of Using Constants

What is a Constant?

• A variable whose value cannot be changed
• Defined using the final keyword
• Naming conventions:
  • All uppercase letters
  • Snake case (e.g., CONSTANT_NAME)
• Syntax error if value is changed

Creating a Constant

• Syntax: final data_type CONSTANT_NAME = value;
• Example:

  final String COMPANY_NAME = "Nazar Academy";
  System.out.println(COMPANY_NAME);
  

Benefits of Using Constants

1. Prevent Accidental Changes:
   • Value can't be altered, preventing mistakes
2. Reuse of Values:
   • Avoids typing the same value multiple times
   • Easy to update value in one place
3. Improved Readability:
   • Descriptive names make the code easier to understand

Demonstration in IDE

• Example project creation and constant implementation
• Steps to create a new project in IDE:
  • File > New Project > Next > Project from template > Next
  • Name project, e.g., Nazar Academy
  • Option to change package name
  • Finish project setup
• Implementing and printing a constant:

  final String COMPANY_NAME = "Nazar Academy";
  System.out.println(COMPANY_NAME);
  

• Attempting to reassign a constant displays an error:

  COMPANY_NAME = "Another Name"; // Error: Cannot assign a value to final variable
  

• Declaration and assignment split:

  final String COMPANY_NAME;
  COMPANY_NAME = "Nazar Academy"; // First-time assignment allowed
  

• Duplicating and fixing typo example:
  • Typing mistake Nazar instead of Nazar
  • Using constant to avoid multiple fixes
  • Updating constant updates all instances

  final String COMPANY_NAME = "Nazar Academy"; // Corrects mistake everywhere
  

Summary

• Constants ensure unchangeable values
• Prevent errors and duplicates
• Enhance code readability

End of Lecture