My Android App is crashed when I register SensorManager.registerListener - sensormanager

Question

Below is my code. I am having a problem when I call SensorManager.registerListener, my app will crash. Can someone tell me what's going on?
I just follw the web guide to setup SensorManger, Sensor(Accelerometer) and then register the action lintener to detect the montion of accelerometer.
I used API 21 to develop this app.
public class MainActivity extends ActionBarActivity implements SensorEventListener{
private TextView tip;
private SensorManager mSensorManager;
private Sensor mSensor;
private float axisX = 0;
private float axisY = 0 ;
private float axisZ = 0;
#Override
protected void onResume() {
super.onResume();
setUpAcceleratorSensor();
mSensorManager.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_NORMAL);
}
#Override
protected void onPause() {
super.onPause();
mSensorManager.unregisterListener(this);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setUpAcceleratorSensor();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private void setUpAcceleratorSensor(){
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
if((mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER)) != null);
else
Toast.makeText(this, "No Sensor Device Exist", Toast.LENGTH_LONG).show();
}
#Override
public void onSensorChanged(SensorEvent event) {
// TODO Auto-generated method stub
Sensor mySensor = event.sensor;
if (mySensor.getType() == Sensor.TYPE_ACCELEROMETER) {
if(event.values[0] != 0 || event.values[1] != 0 || event.values[2] != 0){
axisX = event.values[0];
axisY = event.values[1];
axisZ = event.values[2];
tip.setText("Detect your montion");
}
}
else
Toast.makeText(this, "Cannot Get Sensor Device", Toast.LENGTH_LONG).show();
}
#Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// TODO Auto-generated method stub
}
}
Thanks.

Answer 1

First that I always check when something like this goes wrong, is to check that you have all the correct permissions in the Android Manifest; however, I don't believe that there are any permissions associated with using the position sensors. I would check on this first. That is what comes to mind first, after you post logcat, we will be able to give a more detailed answer.

Answer 2

Try getting the sensor this way
mSensor = mSensorManager.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0); instead in your setUpAccelerometer() method.