ScriptRunner - find number of days between two custom date fields

Question

Can anyone provide scriptrunner cloud, workflow post function, run script code to calculate the number of days between two custom field dates.

I've seen the code below but the first two lines give an error...

Thanks.

import com.atlassian.jira.component.ComponentAccessor;
import com.atlassian.jira.issue.Issue;
import  java.util.Date.*

def customFieldManager = ComponentAccessor.getCustomFieldManager();
def dateFieldObject= customFieldManager.getCustomFieldObject('customfield_15968');

def dateFieldObject2= customFieldManager.getCustomFieldObject('customfield_15967');

if(issue.getCustomFieldValue(dateFieldObject) && issue.getCustomFieldValue(dateFieldObject2)) {

def dateValue = issue.getCustomFieldValue(dateFieldObject) as Date
   def dateValue2 = issue.getCustomFieldValue(dateFieldObject2) as Date
   def calculation = (dateValue - dateValue2)
    
   return (calculation as String)
}

Neil Ingram · Answer

The code copied from the adaptavist link provided doesn't compile. It throws up lots of errors when pasted into the "Script Context"

Neil Ingram · Answer

I would like the result (dateDifference) to be stored in custom field "Cycle Time" so it can be queried with JQL.

Neil Ingram · Answer

I would like the result (dateDifference) to be stored in custom field "Cycle Time")