ConcurrentDictionary中的 TryRemove

    class A
        {
            internal int value;
        }

    ConcurrentDictionary<int, A> dic = new ConcurrentDictionary<int, A>();
                dic.TryAdd(1, new A() {value = 1});
                dic.TryAdd(2, new A() {value = 2});

                A a;
                bool flag;
                flag = dic.TryRemove(2, out a);
                Console.WriteLine(flag);
                if(a == null)
                    Console.WriteLine("a==null");
                else
                {
                    Console.WriteLine($"a.value={a.value}");
                }

                flag = dic.TryRemove(3, out a);
                Console.WriteLine(flag);
                if(a == null)
                    Console.WriteLine("a==null");

移除成功

True
a.value=2

移除失败
False
a==null