Question

希望你不介意，我可能会遗漏一些东西;我只需要对以下场景做一些澄清：如果对象 a 包含对静态列表的引用以及该静态列表中的条目，并且对象 < em> a 超出范围，是否会被垃圾收集？我是否需要将对象 a 引用设置为静态列表，并在该列表中的条目符合条件之前将其引用为null？

我知道静态列表包含将在应用程序的生命周期中存在的对象，所以我在想，因为对象 a 仍引用该静态列表中的条目，它仍然存在于仍然存在的对象的主依赖对象图中？

提前致谢

Answer 1

在你的情况下，静态列表将存在，但 a 将被垃圾收集，因为你无法从任何其他地方访问它，并且没有意义将它保存在内存中。您不需要对静态列表进行空引用。

Answer 2

首先，对象不会超出范围，变量会超出范围。差异是大多数时候的语义之一，但在这里至关重要。

让我们创建一个你所谈论的具体例子：

private static List<string> static_strings = new List<string>();//this won't be
                                                                //collected unless we
                                                                //assign null or another
                                                                //List<string> to static_strings
public void AddOne()
{
  string a = new Random().Next(0, 2000).ToString();//a is in scope, it refers
                                                   //to a string that won't be collected.
  static_strings.Add(a);//now both a and the list are ways to reach that string.
  SomeListHolder b = new SomeListHolder(static_strings);//can be collected
                                                        //right now. Nobody cares
                                                        //about what an object refers
                                                        //to, only what refers to it.
}//a is out of scope.
public void RemoveOne()
{
  if(static_strings.Count == 0) return;
  a = static_strings[0];//a is in scope.
  static_strings.RemoveAt(0);//a is the only way to reach that string.
  GC.Collect();//Do not try this at home.
  //a is in scope here, which means that we can write some code here
  //that uses a. However, garbage collection does not depend upon what we
  //could write, it depends upon what we did write. Because a is no
  //longer used, it is highly possible that it was collected because
  //the compiled code isn't going to waste its time holding onto referenes
  //it isn't using.
}

如此处所示，范围无关紧要，可达性就是一切。

对于引用静态的对象，它引用的内容是无关紧要的，只有引用它的内容。

请注意，这意味着循环引用不会阻止收集项目，这与某些引用计数的垃圾收集方法不同。

对象引用静态成员垃圾处理

2 个答案: