Getting a list of values from dictionary

Question

I'm beginner in c#, and I'm trying to get a list of values but I get a null object reference.

I have a dictionary

var stripes = new Dictionary<int, List<Transform>>();

and I'm trying to get the list of transforms

 foreach (var stripe in stripes) { List<Transform> transforms = stripe.Value; foreach (var treeTransform in transforms) { float distance = DistanceToCameraPlane(treeTransform.position); TreeObject treeObject = new TreeObject(); treeObject.distance = distance; treeObject.tree = treeTransform; sortedTrees.Add(treeObject); } }

However I get a null object references in treeTransform.position

Your problem is not iterating your dictionary, your problem is that the value added to the dictionary is null and when you try to used it throw a null reference exception. — Alexander Leyva Caro
– Alexander Leyva Caro, Commented Mar 4, 2015 at 13:11
you should check why you have null elements inside your transforms collection. Since you get the NullReferenceException on the treeTransform.position line, which means treeTransform is null somehow — cgijbels
– cgijbels, Commented Mar 4, 2015 at 13:12

David Watts · Accepted Answer · 2015-03-04 13:17:05Z

1

Try to change this line:

foreach (var stripe in stripes)

to this instead:

foreach (List<Transform> transforms in stripes.Values)

and remove this:

List<Transform> transforms = stripe.Value;

edited Mar 4, 2015 at 13:17

David Watts

2,28922 silver badges33 bronze badges

answered Mar 4, 2015 at 12:57

Łukasz Rejman

1,8921 gold badge11 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Mat J Over a year ago

Consider explaining why that helps.

Lokesh B R · Accepted Answer · 2015-03-04 13:00:58Z

foreach (var stripe in stripes) { List<Transform> transforms = stripe.Value; if (transforms != null && transforms.Count > 0) { foreach (var treeTransform in transforms) { if (treeTransform != null) { float distance = DistanceToCameraPlane(treeTransform.position); TreeObject treeObject = new TreeObject(); treeObject.distance = distance; treeObject.tree = treeTransform; sortedTrees.Add(treeObject); } } } }

Collectives™ on Stack Overflow

Getting a list of values from dictionary

2 Answers 2

1 Comment

1 Comment

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Related