Static Variables

Static Variables

About

• Class-Level Storage: Associated with class not instances
• Shared State: Visible to all instances
• Memory Efficiency: Single allocation
• Use Cases: Constants, counters, caches

Main Topics

1. Basic Declaration

   • Definition: static keyword
   • Example:

     class Counter {
       static int _totalCount = 0;
     }

2. Constants

   • Definition: Compile-time values
   • Example:

     class MathConstants {
       static const double pi = 3.14159;
     }

3. Mutable State

   • Definition: Shared modification

   • Example:

     class InstanceTracker {
       static int _count = 0;
     
       InstanceTracker() {
         _count++;
       }
     }

4. Lazy Initialization

   • Definition: Late initialization

   • Example:

     class Config {
       static late final String _apiKey;
     
       static void init(String key) {
         _apiKey = key;
       }
     }

5. Visibility

   • Definition: Public vs private
   • Example:

     class Logger {
       static const bool _debug = true;
       static int publicCounter = 0;
     }

How to Use

• Constants: Use static const
• Shared State: Track class-level data
• Configuration: Store app-wide settings
• Memory: Avoid per-instance duplication

How It Works

1. Storage: Single memory location
2. Access: Via class name
3. Lifetime: Matches program execution
4. Threading: No built-in synchronization

Example:

class AppSettings {
  static const String appName = 'MyApp';
  static late String apiBaseUrl;
  static int _requestCount = 0;

  static void incrementRequestCount() {
    _requestCount++;
  }
}

Conclusion

Static variables provide efficient class-level storage for constants, counters, and shared configuration. When used judiciously, they can reduce memory usage and provide convenient access to common data without requiring instance creation.