ConcurrentDictionary<TKey, TValue>.AddOrUpdate Method
.NET Framework 4.5
Adds a key/value pair to the ConcurrentDictionary<TKey, TValue> if the key does not already exist, or updates a key/value pair in the ConcurrentDictionary<TKey, TValue> if the key already exists.
This member is overloaded. For complete information about this member, including syntax, usage, and examples, click a name in the overload list.
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AddOrUpdate(TKey, Func<TKey, TValue>, Func<TKey, TValue, TValue>) | Uses the specified functions to add a key/value pair to the ConcurrentDictionary<TKey, TValue> if the key does not already exist, or to update a key/value pair in the ConcurrentDictionary<TKey, TValue> if the key already exists. |
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AddOrUpdate(TKey, TValue, Func<TKey, TValue, TValue>) | Adds a key/value pair to the ConcurrentDictionary<TKey, TValue> if the key does not already exist, or updates a key/value pair in the ConcurrentDictionary<TKey, TValue> by using the specified function if the key already exists. |
The following example shows how to call the AddOrUpdate method:
class CD_GetOrAddOrUpdate { // Demonstrates: // ConcurrentDictionary<TKey, TValue>.AddOrUpdate() // ConcurrentDictionary<TKey, TValue>.GetOrAdd() // ConcurrentDictionary<TKey, TValue>[] static void Main() { // Construct a ConcurrentDictionary ConcurrentDictionary<int, int> cd = new ConcurrentDictionary<int, int>(); // Bombard the ConcurrentDictionary with 10000 competing AddOrUpdates Parallel.For(0, 10000, i => { // Initial call will set cd[1] = 1. // Ensuing calls will set cd[1] = cd[1] + 1 cd.AddOrUpdate(1, 1, (key, oldValue) => oldValue + 1); }); Console.WriteLine("After 10000 AddOrUpdates, cd[1] = {0}, should be 10000", cd[1]); // Should return 100, as key 2 is not yet in the dictionary int value = cd.GetOrAdd(2, (key) => 100); Console.WriteLine("After initial GetOrAdd, cd[2] = {0} (should be 100)", value); // Should return 100, as key 2 is already set to that value value = cd.GetOrAdd(2, 10000); Console.WriteLine("After second GetOrAdd, cd[2] = {0} (should be 100)", value); } }
