无法在Android Studio中识别sensorEvent

Question

I'm trying to make a compass in a fragment for android. I followed some courses online and read the documentation, but i'm getting the error as said in the title.

my code is this:

 public void onSensorChanged(SensorEvent event) {
    final float alpha = 0.97f;

    synchronized (this){

        if(sensorEvent.sensor.getType()  == Sensor.TYPE_ACCELEROMETER){
            mGravity[0] = alpha * mGravity[0] + (1 - alpha) * sensorEvent.values[0];
            mGravity[1] = alpha * mGravity[1] + (1 - alpha) * sensorEvent.values[1];
            mGravity[2] = alpha * mGravity[2] + (1 - alpha) * sensorEvent.values[2];


        }
        if(sensorEvent.sensor.getType()  == Sensor.TYPE_MAGNETIC_FIELD){
            mGeomagnetic[0] = alpha * mGeomagnetic[0] + (1 - alpha) * sensorEvent.values[0];
            mGeomagnetic[1] = alpha * mGeomagnetic[1] + (1 - alpha) * sensorEvent.values[1];
            mGeomagnetic[2] = alpha * mGeomagnetic[2] + (1 - alpha) * sensorEvent.values[2];
        }

        float R[] = new float[9];
        float I[] = new float[9];
        boolean succes = SensorManager.getRotationMatrix(R,I, mGravity, mGeomagnetic);

        if(succes){
            float orientation[] = new float[3];
            SensorManager.getOrientation(R, orientation);
            azimuth = (float) Math.toDegrees(orientation[0]);
            azimuth = (azimuth + 360) % 360;

            Animation animation = new RotateAnimation(-correctAzimuth, azimuth, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
            correctAzimuth = azimuth;
            animation.setDuration(500);
            animation.setFillAfter(true);
            imageBoussole.startAnimation(animation);
        }

    }
}

in the synchronized bloc the sensorEven is not recognized by android studio. Here are my imports:

import android.content.Context; 
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

Answer 1

The first occurrence of sensorEvent in your code is here:

if(sensorEvent.sensor.getType()  == Sensor.TYPE_ACCELEROMETER){

sensorEvent is not defined anywhere in the code in your listing. It is not surprising that Android Studio does not know what to do with it.

You named the parameter to your method event , not sensorEvent :

public void onSensorChanged(SensorEvent event) {

So, change that to:

public void onSensorChanged(SensorEvent sensorEvent) {

Or, change all references to sensorEvent to be event . The method parameter and your uses of that parameter need to match.