I'm trying to compare number of business hours with number of hours (bh<48) I have gone through few methods and tried the below method to get number of hours(difference between startdate and enddate :

diff(BusinessHours.id, startdate, Datetime.now())<48)

But I'm constantly getting the same error for all the methods : "Method does not exist or incorrect signature: [BusinessHours].diff(Schema.SObjectField, Datetime, Datetime)"

I dont understand this error as usage of methods are referred here

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_businesshours.htm

Any suggestions are highly appreciated! TIA

//Trigger to compare business hours with specific number of hours in apex trigger and update the case status value Trigger Test_Business_hours_Trigger on emailmessage (before insert,after insert,before update,after update) { // case cas {get;set;} long l;

Case cas = [SELECT ClosedDate, status FROM Case WHERE ClosedDate != NULL LIMIT 1];

//SOQL query to get the business hours defined in the org BusinessHours bh = [Select id,SundayStartTime, MondayStartTime, TuesdayStartTime, WednesdayStartTime, ThursdayStartTime, FridayStartTime, SaturdayStartTime, SundayEndTime, MondayEndTime,TuesdayEndTime, WednesdayEndTime, ThursdayEndTime, FridayEndTime,SaturdayEndTime From BusinessHours Where IsDefault=true]; //gets closed date and system.now() in to the variables to define in business hours bh.diff() method DateTime startdate = cas.ClosedDate ; DateTime systemnow = system.now();

    long startl = startdate.getTime();
    long nowl   = systemnow.getTime();

// assigning the number of hours(business hours) i.e, the difference between the startdate and systemnow in to variable 'l' l = businesshours.diff(bh.id,startdate,systemnow); system.debug(l); //For trigger.new values if status is closed and number of business hours are less than 48 hours(172800000 milliseconds) then updates the status to working For(Emailmessage em : trigger.new){ if((Cas.Status=='Closed') && (l<172800000)) { cas.status='Working'; update Cas; } } }