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控制队列(或列表)的容量

collections c#

Bastien Vandamme · 技术社区 · 4 年前

我有课

    public class ProductionQueue
    {
        /// <summary>
        /// Gets or sets the title.
        /// </summary>
        /// <value>
        /// The title.
        /// </value>
        public string? Name { get; set; }

        /// <summary>
        /// Maximum capacity of the queue. Keep it null for inifinte capacity.
        /// </summary>
        public TimeSpan? Capacity { get; set; }

        /// <summary>
        /// Gets or sets the tasks.
        /// </summary>
        /// <value>
        /// The tasks.
        /// </value>
        public IList<Task> Tasks { get; set; } = new List<Task>();
    }

让我解释一下,Task对象还包含一个变量(可能是另一个Timespan),该变量包含执行任务的时间。

当我在任务列表中添加新任务时,如果达到了我的容量,是否可以在我的ProductionQueue中添加事件、观察者或任何其他行为来引发异常?

0 回复 | 直到 4 年前

XouDo Sagar Tambade 4 年前

我已经根据您的初始代码编写了这个简单的解决方案,但使用 ObservableCollection ,因此每次修改集合时都可以检查容量。

可以使用 NotifyCollectionChangedEventArgs (修改类型、NewItems、OldItems等),只重新计算更改的内容,而不是每次迭代整个集合。

   // simple object for the sake of this example
   public class Task
   {
       public TimeSpan TimeToPerform;
   }

   public class ProductionQueue
   {
       public string? Name { get; set; }

       /// <summary>
       /// Maximum capacity of the queue. Keep it null for inifinte capacity.
       /// </summary>
       public TimeSpan? Capacity { get; set;}
               
       public ObservableCollection<Task> Tasks = new ObservableCollection <Task>();
       
       // ProductionQueue ctor
       public ProductionQueue(TimeSpan? initialCapacity)
       {
           this.Capacity = initialCapacity;

           // subscribe to know when the collection gets changed
           this.Tasks.CollectionChanged += (s, e) => { 
               Console.WriteLine("collection changed");               
               this.checkCapacity();                
           };  
       } 
       
       private void checkCapacity()
       {
           var totalTime = TimeSpan.Zero;
               
           foreach (var task in this.Tasks)
           {
               totalTime+= task.TimeToPerform;
           }
           
           if (totalTime > this.Capacity)
               throw new Exception("queue time capacity exceeded");           
       }
   }
}

下面是一个使用它的程序示例:

public static void Main(string[] args)
{
    try
    {
        var PQ = new ProductionQueue(TimeSpan.FromHours(1));

        PQ.Tasks.Add(new Task(){ TimeToPerform=TimeSpan.FromMinutes(40)});
        PQ.Tasks.Add(new Task(){ TimeToPerform=TimeSpan.FromMinutes(30)});

        Console.WriteLine("Tasks added without problem");
    }
    catch(Exception e)
    {
        Console.WriteLine("Exception occured: "+e.Message);
    }
}

控制台输出:

collection changed
collection changed
Exception occured: queue time capacity exceeded