Batch error: Attempt to de-reference a null object with check for !=null

Question

I have a batch apex where I insert some records. I check on the fields for != null but still get the error:

Attempt to de-reference a null object

Here is my batch part:

global void execute(Database.BatchableContext bc, List<Relatie_Contact__c> scope){
        // process each batch of records  

        if(scope.size()!=Null){
            for (Relatie_Contact__c rc : Scope){
                if(Scope.size() > 0) {

                    if(rc.Contactpersoon__r.Birthdate.year() !=null){
                    Integer St=System.Today().year()- rc.Contactpersoon__r.Birthdate.year();

                    Id relatietype;
                    if(rc.relatietype__c == 'Zomer Challenge' && rc.relatietype__c!=null){ 
                        relatietype = relatietype4[0].id;
                    }

                        if(St < 6 && rc.relatietype__c != 'Zomer Challenge' && rc.relatietype__c!=null){ 
                            relatietype = relatietype3[0].id;
                        }
                        if(St > 5 && St <= 17 && rc.relatietype__c != 'Zomer Challenge' && rc.relatietype__c!=null){  
                            relatietype = relatietype2[0].id;
                        }
                        if(St > 17 && rc.relatietype__c != 'Zomer Challenge' && rc.relatietype__c!=null){  
                            relatietype = relatietype1[0].id;
                        }

                    //If Referentie__c > 50 characters --> error in servicebus     
                    if(rc.Contactpersoon__r.Bondsnummer__c != null && rc.Contactpersoon__r.Name !=null){
                    Intlenght = (String.valueOf(rc.Contactpersoon__r.Bondsnummer__c +' / ' + rc.Contactpersoon__r.Name)).length();
                    if(Intlenght >49 ){subjectInput = (rc.Contactpersoon__r.Bondsnummer__c +' / ' + rc.Contactpersoon__r.Name).subString(0,49) ;}
                    if(Intlenght <49 ){subjectInput = (rc.Contactpersoon__r.Bondsnummer__c +' / ' + rc.Contactpersoon__r.Name);}     
                    }
                    Factuurregel__c fa =new Factuurregel__c(Organisatie__c=rc.Organisatie__c , Debiteur__c =rc.Organisatie__r.Debiteurennummer__c,
                                                            Aantal__c = 1, AFAS_ID__c=relatietype, Factuurdatum__c= date.today(), 
                                                            Contactpersoon__c = rc.Contactpersoon__c, Referentie__c = subjectInput
                                                           );
                    fact.add(fa); 
                } 
            }}insert fact; fact.clear();}
    }    

The following line seems to throw the error:

Integer St=System.Today().year()- rc.Contactpersoon__r.Birthdate.year();

Answer 1

The error probably comes from the if statement itself. If the Birthdate field is set to null, you can't call the year() method on it. You should check if the Birthdate field is not null. – Martin Lezer May 2 at 9:33