java - 如何在AsyncTask doInBackground()中使用同步对象？

Question

我在后台线程中使用同步对象时遇到了麻烦。我已经在示例中详细说明了问题:

1. 我编写了这样的简单类:

   public class UIThreadClass {
   
      MyObject object;
   
      UIThreadClass() {
         object = new MyObject();
   
         object.doActionOne();
         object.doActionTwo();
     }
   }
   

2. 现在我的任务是通过将两个方法放入非 UI 线程来改进代码。 我正在使用 AsyncTask

   对于 doActionOne()

   private static class DoActionOneTask extends AsyncTask<Void, Void, Void> {
   
       private WeakReference<MyObject> wObject;
   
       DoActionOneTask(MyObject object) {
           wObject = new WeakReference<>(object);
       }
   
       @Override
       protected Void doInBackground(Void... voids) {
          if(wObject.get() != null) {
             MyObject myObject = wObject.get();
             myObject.doActionOne();
          }
   
          return null;
       }
   }
   

   对于 doActionTwo()

   private static class DoActionTwoTask extends AsyncTask<Void, Void, Void> {
   
       private WeakReference<MyObject> wObject;
   
       DoActionOneTask(MyObject object) {
           wObject = new WeakReference<>(object);
       }
   
       @Override
       protected Void doInBackground(Void... voids) {
          if(wObject.get() != null) {
             MyObject myObject = wObject.get();
             myObject.doActionTwo();
          }
   
          return null;
       }
   }
   

   现在在 UI 线程中调用它们

   public class UIThreadClass {
   
      MyObject object;
   
      UIThreadClass() {
         object = new MyObject();
   
         new DoActionOneTask(object).execute();
         new DoActionTwoTask(object).execute();
     }
   }
   

问题是:

When using AsyncTask - how to synchronized the object to make sure that the doActionTwo() alway call after doActionOne() method ?.

我尝试在 doInBackground() 中使用 synchronized (myObject) {myObject.doActionOne();} 但系统警告我 myObject 只是局部变量，很难保证正确性。

任何人都可以帮助我解决这种情况吗？非常感谢!

Answer 1

您无需执行任何操作。它们将按照 Android 文档串行执行

Order of execution
When first introduced, AsyncTasks were executed serially on a single background thread. Starting with DONUT, this was changed to a pool of threads allowing multiple tasks to operate in parallel. Starting with HONEYCOMB, tasks are executed on a single thread to avoid common application errors caused by parallel execution.

If you truly want parallel execution, you can invoke executeOnExecutor(java.util.concurrent.Executor, Object[]) with THREAD_POOL_EXECUTOR.