在Firebase中的多个地点接收数据后继续执行 [英] Continue execution after data received from multiple location in Firebase

问题描述

我知道这可能是一个常见的问题，但我真的坚持在这一点上。

我从2个地方接收数据，从两个地方收到数据后，我需要继续执行，并将数据返回给调用方法。

我知道这个线程： https://stackoverflow.com/ a / 33204705/1820644 ，但实际上这并不适合，因为我需要将数据返回给调用方法。

对于阻塞UI线程的方法，我可以从 AsyncTask 调用它，这是没有问题的。但是，我怎样才能返回数据到调用方法，我已经成功地完成执行。

这是我的助手类里面

  //这个方法应该在AsyncTask中调用
 public boolean doComputation（）{
 DatabaseReference ref = FirebaseDatabase.getInstance（）。getReference（）。child activity）
 .child（id）; 
 $ b $ ref.child（path1）。addListenerForSingleValueEvent（new ValueEventListener（）{
 @Override 
 public void onDataChange（DataSnapshot dataSnapshot）{
 // Call 1已完成
} 
 
 @Override 
 public void onCancelled（DatabaseError databaseError）{
 
 
}）; 
 
 ref.child（path2）。addListenerForSingleValueEvent（new ValueEventListener（）{
 @Override 
 public void onDataChange（DataSnapshot dataSnapshot）{
 // Call 2已完成
} 
 
 @Override 
 public void onCancelled（DatabaseError databaseError）{
 
 
}）; 
 
 //一些要做的事
 
 //执行完成后需要返回true 
 return true; 
 
 
 
 $ b 
我不能在里面返回true onDataChange ，因为它会计入 onDataChange 方法，而不是用于 doComputation 。
 
 
 
我可以通过将其移动到另一个方法来执行计算，并且在每个onDataChange回调之后，我可以检查变量计数，如果是 2 ，则可以执行计算。但完成后，我需要通知调用方法，执行已完成。
 
 
这是有点棘手， Firebase 。但是，我现在真的被困住了。任何帮助将不胜感激。谢谢。
解决方案 
我已经用了 Tasks API 已经使用了。它是伟大的。 
 
 
正如@qbix所述，这个答案做同样的事情。答案中的例子很好解释。  
 
 
你也可以找到这个API说明的视频链接这里。 
 
 
 
我已经试过并测试过了。解决我的问题。
 
I know this might be a common question but I am really stuck at this point. 

I am receiving data from 2 multiple locations and after I received from both I need to continue executing and than return that data to the calling method. 

I am aware of this thread: https://stackoverflow.com/a/33204705/1820644 but it doesn't fit here actually as I need to return the data to the calling method. 

For the method that blocks UI thread I can call it from AsyncTask, there is no problem. But how can I return data to the calling method that I have successfully completed execution.

This is inside my helper class
// This method should be called in AsyncTask
public boolean doComputation() {
        DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("activity")
                .child(id);

        ref.child("path1").addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
               // Call 1 completed
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

        ref.child("path2").addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
               // Call 2 completed
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

        // Some more to do

        // Need to return true after execution complete
        return true;
}
I can not return true inside of the onDataChange as it will counted for onDataChange method and not for doComputation.

I can perform the calculation by moving it to another method and after each onDataChange callback I can check for variable count, and if it is 2 I can perform the calculations. But after it completes I need to notify it to the calling method that execution is completed.

This is a little bit tricky with Firebase. But, I am really stuck at it right now. Any help will be much appreciated. Thank you.
解决方案
I have gone with the Tasks API which Firebase uses already. Its great.

As mentioned by @qbix , This answer does the same thing. The example in the answer explains good. 

You can also find video link of this API instructions here. 

I have tried and tested it. Solves my problem.

                        
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