Static vs. Instance Context

In Apex, understanding the difference between static and instance context is crucial for designing efficient and maintainable code.

🔹 What is Static Context?

A static variable or method belongs to the class itself, not to any specific instance (object) of that class. You don’t need to create an object to use a static member.

Example: Static Method & Variable

public class Utils {
    public static Integer count = 0;

    public static void logMessage(String msg) {
        System.debug('Log: ' + msg);
        count++;
    }
}  
  

Usage:

Utils.logMessage('Start process');
System.debug(Utils.count); // Output: 1
  

🔹 What is Instance Context?

An instance variable or method belongs to an object created from a class. You need to create an object to use instance members.

Example: Instance Method & Variable

public class Person {
    public String name;

    public Person(String name) {
        this.name = name;
    }

    public void sayHello() {
        System.debug('Hello, I am ' + name);
    }
}
  

Usage:

Person p = new Person('John');
p.sayHello(); // Output: Hello, I am John
  

🔍 Key Differences

Feature	Static	Instance
Belongs To	Class	Object
Accessed Using	Class name	Object reference
Memory Allocation	Once per class	Each time object is created
Example	Utils.logMessage()	p.sayHello()

🧠 Best Practices

• Use static when the behavior or data doesn't depend on object state (e.g., utility functions).
• Use instance when behavior varies per object (e.g., user-specific logic).