在android中使用synchronized()

Question

我有一个android项目，正在使用wait()和notify()，所以某些代码只在后台任务之后执行，这是一个调用firebase的函数：

//Code Snippet 1
 public  Task<String> checkIfJokeSavedFirebase() throws InterruptedException {
        final String[] idToken = {""};
        Map<String, Object> data = new HashMap<>();
        FirebaseUser mUser = FirebaseAuth.getInstance().getCurrentUser();
        mUser.getIdToken(true)
                .addOnCompleteListener(new OnCompleteListener<GetTokenResult>() {
                    public void onComplete(@NonNull Task<GetTokenResult> task) {
                        if (task.isSuccessful()) {
                            idToken[0] = task.getResult().getToken();
                            data.put("token", idToken[0]);
                            String someObject = "test";
                            synchronized (someObject) {
                                Log.d("longdebug","someObject pre notify");
                                someObject.notify();
                            }
                            //notify();
                            // Send token to your backend via HTTPS
                            // ...
                        } else {
                            // Handle error -> task.getException();
                        }
                    }
                });
        String someObject = "test";
        synchronized (someObject){
            Log.d("longdebug","someObject pre wait");
            someObject.wait();
        }
        Log.d("runtimeexception","pre actually called");
        data.put("token", idToken[0]);
        //data.put("jokeid",jokeJSON.getString("id"));
        return FirebaseFunctions.getInstance()
                .getHttpsCallable("checkIfJokeSaved")
                .call(data)
                .continueWith(new Continuation<HttpsCallableResult, String>() {
                    @Override
                    public String then(@NonNull Task<HttpsCallableResult> task) throws Exception {
                        Log.d("runtimeexception",".then");
                        HashMap result = (HashMap) task.getResult().getData();
                        JSONObject res = new JSONObject(result);
                        String jokeStored = res.getString("jokeStored");
                        Log.d("runtimeexception","jokeStored returned");
                        return jokeStored;
                    }
                });
    }

以及我调用函数的代码：：

//Code Snippet 2
 try {
      Log.d("runtimeexception","pre checkSavedCall");
      activity.checkIfJokeSavedFirebase().addOnCompleteListener(new OnCompleteListener<String>() {
                    @Override
                    public void onComplete(@NonNull Task<String> task) {
                        Log.d("runtimeexception","pre task.getResult");
                        Log.d("runtimeexception","task.getResult:" + task.getResult());
                        jokeSaved = Boolean.parseBoolean(task.getResult());
                        String synchronizedChannel = "displaysaved";
                        synchronized (synchronizedChannel){
                            Log.d("runtimeexception","pre notify");
                            synchronizedChannel.notifyAll();
                        }
                    }
                });
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            String synchronizedChannel = "displaysaved";
            synchronized (synchronizedChannel){
                try {
                    Log.d("runtimeexception","pre wait");
                    synchronizedChannel.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

我的代码没有写入代码片段1中的".then“日志，但是当我删除：

synchronized (synchronizedChannel){
                try {
                    Log.d("runtimeexception","pre wait");
                    synchronizedChannel.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

从snippet 2开始，snippet 1进入".then“日志并完成执行。删除wait()语句怎么可能导致对firebase函数的调用结束？

Answer 1

我没有找到同步问题的解决方案，但我只是从AsyncTask切换到RxJava，并将Firebase调用转移到一个任务，这允许我摆脱所有以前的同步语句，并且只需要在任务中使用两个同步语句。