ConcurrentDictionary<TKey,TValue>.TryRemove Method(TKey,TValue):

Attempts to remove and return the value that has the specified key from the System.Collections.Concurrent.ConcurrentDictionary<TKey,TValue>.

Namespace:                   System.Collections.Concurrent
Assembly:         mscorlib (in mscorlib.dll)

Syntax

public bool TryRemove(
	TKey key,	out TValue value
)
Parameters

  • key

  • Type:    TKey

    The key of the element to remove and return.

Return Value

Type:    System.Boolean

true if the object was removed successfully; otherwise, false.

Exceptions

ExceptionCondition
ArgumentNullException

key is  null.

Examples

The following example shows how to call the ConcurrentDictionary<TKey,TValue>.TryRemove method:

class CD_TryXYZ
{        // Demonstrates:
        //      ConcurrentDictionary<TKey, TValue>.TryAdd()
        //      ConcurrentDictionary<TKey, TValue>.TryUpdate()
        //      ConcurrentDictionary<TKey, TValue>.TryRemove()
        static void Main()
        {            
        int numFailures = 0; // for bookkeeping
            // Construct an empty dictionary
ConcurrentDictionary<int, String> cd = new ConcurrentDictionary<int, string>();
            // This should work
            if (!cd.TryAdd(1, "one"))
            {
                Console.WriteLine("CD.TryAdd() failed when it should have succeeded");
                numFailures++;
            }            
            // This shouldn't work -- key 1 is already in use
            if (cd.TryAdd(1, "uno"))
            {
                Console.WriteLine("CD.TryAdd() succeeded when it should have failed");
                numFailures++;
            }            
            // Now change the value for key 1 from "one" to "uno" -- should work
            if (!cd.TryUpdate(1, "uno", "one"))
            {
                Console.WriteLine("CD.TryUpdate() failed when it should have succeeded");
                numFailures++;
            }            // Try to change the value for key 1 from "eine" to "one" 
            //    -- this shouldn't work, because the current value isn't "eine"
            if (cd.TryUpdate(1, "one", "eine"))
            {
                Console.WriteLine("CD.TryUpdate() succeeded when it should have failed");
                numFailures++;
            }            // Remove key/value for key 1.  Should work.
            string value1;            if (!cd.TryRemove(1, out value1))
            {
                Console.WriteLine("CD.TryRemove() failed when it should have succeeded");
                numFailures++;
            }            
            // Remove key/value for key 1.  Shouldn't work, because I already removed it
            string value2;            
            if (cd.)
            {
                Console.WriteLine("CD.TryRemove() succeeded when it should have failed");
                numFailures++;
            }            // If nothing went wrong, say so
            if (numFailures == 0) Console.WriteLine("  OK!");
        }
}


Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1

See Also

ConcurrentDictionary<TKey,TValue> Class
System.Collections.Concurrent Namespace
Thread-Safe Collections
How to: Add and Remove Items from a ConcurrentDictionary

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备注：转自https://msdn.microsoft.com/en-us/library/dd287129(v=vs.110).aspx