什么是同时活动之间切换的Andr​​oid应用程序一个单独的“实例”变量变为空的可能性有多大？ [英] What are the chances a singleton's 'instance' variable becomes null in an android app while switching between Activities?

问题描述

我有一个单身，典型的设计使用静态'mInstance保持全局状态。我注意到，有时，虽然活动之间切换时，mInstance变量变为无效，并要求重新实例化，导致所有数据走空。

I have a singleton, typical design with a static 'mInstance' to hold the global state. I notice that sometimes, while switching between activities, the mInstance variable becomes null and requires to be re-instantiated, causing all data to go empty.

这是预期还是我做错了什么？是否真的有机会，一个单身的静态变量将在这样的情况下无效？我严重怀疑它，想听到一些意见。

Is this expected or am I doing something wrong? Is there really a chance that the static variables of a singleton would be nullified in such a scenario? I seriously doubt it and would like to hear some opinions.

code粘贴：

public class RuleManager extends ArrayAdapter<Rule>
{
  private static RuleManager mInstance;
  private final Context context;
  public RuleManager(Context context, List<Rule> r)
  {
    super(context,R.layout.main_menu_options_list_item);
    if(r==null)r=new ArrayList<Rule>();
    this.context=context;
  }

  public static RuleManager getInstance(Context context,List<Rule> r) 
  {
      if (mInstance == null)
          mInstance = new RuleManager(context, r);
      return mInstance;
  }   
}

我刚刚得知存储上下文这样就不会让它被垃圾收集，因此可能造成大的泄漏。

I just learned that storing Context like this would never let it being Garbage Collected and hence may cause a big leak.

推荐答案

您需要让你的构造私人。我猜你可能会调用构造一个新的。也使您的getInstance同步。

You need to make your constructor private. I guess you may be calling a new on the constructor. Also make your getInstance synchronized.

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