Android:“调用线程必须是准备好的Looper线程"我使用AsyncTask时出现错误 [英] Android: "Calling thread must be a prepared Looper thread" error when I use AsyncTask

问题描述

我创建了一个AsyncTask来检索20米精度的GPS位置. 我想执行一段时间的循环直到精度提高为止.

I've created a AsyncTask to retrieve a GPS position with a 20-meter accuracy. I would like to execute a while do cycle until accuracy is accetable.

问题是我请求更新职位时遇到异常.

The problem is that I got an exception when I request an update of position.

java.lang.NullPointerException: Calling thread must be a prepared Looper thread.

这是出错的代码

@Override
protected String doInBackground(Void... params) {
if (ActivityCompat.checkSelfPermission(activity, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(activity, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                return null;
            }
            mLocationRequest.setInterval(100);
            mLocationRequest.setPriority(100);
            mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
            while (mLastLocation == null || (mLastLocation.getAccuracy()>Float.parseFloat("20.0") && mLastLocation.hasAccuracy())){
                try {
                    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,mLocationRequest,activity);
                    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
                } catch (SecurityException secex) {

                }
            }

            return null;
        }

推荐答案

我在整天的工作中都遇到了麻烦.我在服务内部的后台运行了FusedLocationApi.

I had troubles with this a full work day. I have the FusedLocationApi running in background within a Service.

我所做的-我在其他地方读过-添加Looper.getMainLooper()作为requestLocationUpdates()的最后一个参数.

What I a did -I read it somewhere else- is add Looper.getMainLooper() as the last parameter of requestLocationUpdates().

所以，而不是这个

LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,mLocationRequest,activity);

您将拥有

LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this, Looper.getMainLooper());

如果您阅读了整个 FusedLocationProviderApi 页面上，您会看到该方法将根据参数执行不同的操作.

If your read the whole FusedLocationProviderApi page, you will see that the method will do different thing depending on the parameters.

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