Java单例设计模式与全局变量

Question

I have developed a "Quiz application in java", which have many features like quiz conduction, instant reporting features, students can post their doubts and all.

I want to maintain the log of the number of students requested for quiz, the number of students that submitted the response, the total active students and some other details.

I am using a Global class which has static variables to keep these details. Is it correct way to maintain this or should I want to use the Singleton design pattern ?

Kindly give me pros and cons of both and which one to use and when?

Answer 1

Long story short: by using global variables you're breaking OOP rules (encapsulation). You will keep using them until your code becomes one big mess. So instead of using global variables I would go for singleton (but make sure it is thread safe). Neither solutions are great thought.

PS There is a lot of information on the internet:

• Should I use global variables here?
• How to create a manager class without global variables nor singletons?
• Why are static variables considered evil?
• Avoid Global Variables, Environment Variables, and Singletons