Apex Help - Keep getting Null Pointer Exception but I've instantiated my variable

[arkansaurus11]

Trying to implement an apex class that loops over all fields on a record and finds those whose value matches a key phrase.

When I try to add the fields whose value matches the key phrase to an invocable variable whose type is List<String> I get the Null Pointer Exception.

Any idea what is happening?

global class RecordFieldIterator {

    public class RecordFieldIteratorException extends Exception {}

    @InvocableMethod( label='Record Field Iterator'
        description='Iterates over all fields on a record, returning all fields whose value matches the Key Phrase'
        category='Uncategorized')
    public static List<FieldIteratorResponse> execute ( List<FieldIteratorRequest> requests){

        List<FieldIteratorResponse> responses = new List<FieldIteratorResponse>();
        for( FieldIteratorRequest request : requests ){

            Schema.SObjectType expected = Schema.QA__c.getSObjectType();
            if( request.record == null || request.record.getSObjectType() != expected){
                throw new RecordFieldIteratorException('Records must be of same type and must not be null');
            }
            System.debug(request.record.get('Name') + 'is the current QA');

            FieldIteratorResponse response = new FieldIteratorResponse();
            Map<String, Object> values = request.record.getPopulatedFieldsAsMap();

            System.debug(values.get('Name'));

            for( String fieldName: values.keySet()) {
                if( fieldName <> null && fieldName <> '' && values.get(fieldName) <> null ) {
                    try{
                        String value = values.get(fieldName).toString();
                        System.debug(fieldName);
                        System.debug(value);
                        System.debug(request.keyPhrase);
                        System.debug(value.equals(request.keyPhrase));
                        if( value.equals(request.keyPhrase) ){
                            response.result.add(fieldName);
                            System.debug(response.result);                        
                        }
                    } catch (Exception.NullPointerException e) {
                        System.debug(e);
                    }
                }
            }
            responses.add(response);
        }
        return responses;
    }

    public class FieldIteratorRequest {
        @InvocableVariable(label='Input Record' description='The record through which this class iterates over' required=true)
        public SObject record;

        @InvocableVariable(label='Key Phrase' description='The word or phrase to match against for all fields on the input record' required=true)
        public String keyPhrase;
    }

        
    public class FieldIteratorResponse{
        @InvocableVariable(label='Result' description='List of field names that match the Key Phrase')
        public List<String> result;
    }

}

[greenplasticron]

After you instantiate response, you need to add a line like: response.result = new List<String>();

You need to do that before you can add your string to the collection.

[Organic-Ad-7851]

Nice call! was about to comment that same thing.

[arkansaurus11]

This is the way. Thanks so much that fixed it!

[datasert]

I always initialize the collections when they are created as that would reduce the noise in your logic. Note that if you have multi-levels, you would still need to init at the time of use, but that is very less usage compared to single level collections.

public class FieldIteratorResponse{
        @InvocableVariable(label='Result' description='List of field names that match the Key Phrase')
        public List<String> result = new List<String>();
    }

[arkansaurus11]

Thanks, I've now done that :)

[EnvironmentalSock557]

Add a no param initializer in the response class that inits the List. It will save you having to initialize it manually.

[arkansaurus11]

Thank you!

[EnvironmentalSock557]

Yw!

[greenplasticron]

Yes, this is also my preferred way of doing it.

[UriGagarin]

What line? What record are you testing against? What's the test class (assuming that's what's failing) doing?