java - getLastLocation().addOnSuccessListener 在按钮中不起作用

Question

我想设置一个按钮，当我按下按钮时，然后获取位置。

FusedLocationProviderClient userLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);

这可以在onCreate中工作，但我想设置一个按钮，当我放置按钮时， 然后显示用户位置。这是行不通的。这是我的代码，我该如何修复它？

public class MainActivity extends AppCompatActivity{

final private int userAgreePermissionCode = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //  Check permission and go "onRequestPermissionsResult"
    int currentPermission = ActivityCompat.checkSelfPermission(this,android.Manifest.permission.ACCESS_FINE_LOCATION);
    if( currentPermission!=PackageManager.PERMISSION_GRANTED ) ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, userAgreePermissionCode);



    findViewById(R.id.Locate).setOnClickListener(new View.OnClickListener() {
        @SuppressLint("MissingPermission")
        @Override
        public void onClick(View v) {
            //  can't work
            FusedLocationProviderClient userLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);  //  Error in here!!
            userLocationProviderClient.getLastLocation().addOnSuccessListener(new OnSuccessListener<Location>() {
                @Override
                public void onSuccess(Location location) {
                    Log.i("Longitude:", location.getLongitude()+"");
                    Log.i("Latitude:", location.getLatitude()+"");
                }
            });
        }
    });
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestCode) {
        case userAgreePermissionCode:
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // Permission Granted
                Log.i("Status:","Granted");
            } else {
                // Permission Denied
                finish();
            }
            break;
        default:
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }

}

}

Answer 1

它不起作用，因为该范围内的 this 引用了 View.OnClientListener 的实例。

您可以通过放置 MainActivity.this 来修复它，或者您可以将 FusedLocationProviderClient 作为成员字段，在 onCreate 中实例化它，然后在您的点击监听器中使用它。