Dictionary throws exception even after checked for null

Question

I am trying to read a value of a key from a dictionary like the following :

if (myDic["myKey"] != null)
{
}

I can see that I am checking for null, but even then it throws KeyNotFoundException. How else should I check this? Please advise!

Answer 1

It looks like you're confusing the behavior of HashTable with that of Dictionary<TKey, TValue>. The HashTable class will return a null value when the key is not present while Dictionary<TKey, TValue> will throw an exception.

You need to either use ContainsKey or TryGetValue to avoid this problem.

object value;
if (myDic.TryGetValue("apple", out value)) {
  ...
}