Question

我希望在点击按钮时获取当前的GPS位置。我编写了这段代码（如下所示），但这为NullPointerException的位置对象提供了Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);。请告诉我的代码有什么问题？

代码：

@Override
public void onClick(View v) {
    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    if (ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
    }
    String cur_loc = "latitude = " + location.getLatitude() + "\n" + location.getLongitude(); //this is line 54 in my code
    Toast.makeText(ctx, cur_loc, Toast.LENGTH_LONG).show();
}

AndroidManifest

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

Answer 1

getLastKnownLocation (String provider)可能会返回null。见Documentation：

返回指示上一个已知位置的数据的位置   从给定的提供者处获得的修复。

这可以在不启动提供程序的情况下完成。请注意这一点   位置可能已过时，例如，如果设备已转动   关闭并搬到另一个地方。

如果当前禁用了提供程序，则返回null。

尝试这种方法：

    private Location getLastKnownLocation() {
    mLocationManager = (LocationManager)getApplicationContext().getSystemService(LOCATION_SERVICE);
    List<String> providers = mLocationManager.getProviders(true);
    Location bestLocation = null;
    for (String provider : providers) {
        Location l = mLocationManager.getLastKnownLocation(provider);
        if (l == null) {
            continue;
        }
        if (bestLocation == null || l.getAccuracy() < bestLocation.getAccuracy()) {
            // Found best last known location: %s", l);
            bestLocation = l;
        }
    }
    return bestLocation;
}

现在将其用作：

LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location myLocation = getLastKnownLocation();

onClick获取GPS位置

1 个答案: