Hi, Ganeeesh

Using Static Methods and Variables

You can use static methods and variables only with outer classes. Inner classes have no static methods or variables. A static method or variable doesn’t require an instance of the class in order to run.

Before an object of a class is created, all static member variables in a class are initialized, and all static initialization code blocks are executed. These items are handled in the order in which they appear in the class.

A static method is used as a utility method, and it never depends on the value of an instance member variable. Because a static method is only associated with a class, it can’t access the instance member variable values of its class.

A static variable is static only within the scope of the Apex transaction. It’s not static across the server or the entire organization. The value of a static variable persists within the context of a single transaction and is reset across transaction boundaries. For example, if an Apex DML request causes a trigger to fire multiple times, the static variables persist across these trigger invocations.

To store information that is shared across instances of a class, use a static variable. All instances of the same class share a single copy of the static variable. For example, all triggers that a single transaction spawns can communicate with each other by viewing and updating static variables in a related class. A recursive trigger can use the value of a class variable to determine when to exit the recursion.

some interesting behavior in our test classes when using static variables to make sure triggers only fire once. Consider the following trigger, class, and testclass:

Trigger:

trigger RecursiveTrigger on Account (before insert) {
                       if(RecursiveClass.RunOnce) {
                            RecursiveClass.RunOnce = false;
                            if(Trigger.isInsert) {
                              RecursiveClass.doStuffOnInsert();
    }
                                if(Trigger.isUpdate) {
                               RecursiveClass.doStuffOnUpdate();
                       }
           }
}


Class:
 
  public class RecursiveClass {
          public static boolean RunOnce = true;
                 
             public static void doStuffOnInsert() {}
             public static void doStuffOnUpdate() {}

 }

Testclass:

@IsTest(SeeAllData=false)
public class TestRecursiveClass {

          static testMethod void testAccountInsertUpdate() {
                  Account a = new Account(Name = 'Testing Recursive'); 
                   insert a;
                    a.Name = 'Testing Update';
                     update a;
                   }
    }


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Thanks&Regards,
Syed Jabeena