The method onPause( ), onResume( ) is undefined for the type

Question

I a have class for ShakeListener and i have implemented onPause() and onResume() methods in that. My code for that is

package com.example.shakedemo;

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.content.Context;
import java.lang.UnsupportedOperationException;


public class ShakeListener
{
      private SensorManager mSensorManager;
      private float mAccel; // acceleration apart from gravity
      private float mAccelCurrent; // current acceleration including gravity
      private float mAccelLast; // last acceleration including gravity

  private final SensorEventListener mSensorListener = new SensorEventListener() {

    public void onSensorChanged(SensorEvent se) {
      float x = se.values[0];
      float y = se.values[1];
      float z = se.values[2];
      mAccelLast = mAccelCurrent;
      mAccelCurrent = (float) Math.sqrt((double) (x*x + y*y + z*z));
      float delta = mAccelCurrent - mAccelLast;
      mAccel = mAccel * 0.9f + delta; // perform low-cut filter
    }

    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }


  };



  protected void onResume() {
    super.onResume();
    mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
  }

  protected void onPause() {
    super.onPause();
    mSensorManager.unregisterListener(mSensorListener);

  }
}

But it showing an error on both super.onPause(); and super.onResume(); lines which says

The method onPause() is undefined for the type Object

Is there any problem in implementing onResume and onPause in a class?

As i am a new one in android development please give me clear idea about that.

Answer 1

onResume and onPause are the methods of an Activity class. You are not overriding the activity.

If the ShakeListener is an Activity you need to extends the Activity class. like

public class ShakeListener extends Activity 

And if that is not an Activity class, then do not call super versions.

Just do them as

public void registerListener() {
    mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
  }

  public void unregisterListener() {
    mSensorManager.unregisterListener(mSensorListener);

  }

Answer 2

The problem is that your implementations call the super versions of the methods which don't exist.

protected void onResume() {
    super.onResume(); // <== This line needs to be removed
    mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
}

protected void onPause() {
    super.onPause(); // <== This line needs to go as well
    mSensorManager.unregisterListener(mSensorListener);

}

Either get rid of the super calls (which makes the most sense) or inherit from a class that implements the methods.

Answer 3

You need to make your class a subclass of Activity class, So that you can get the onPause and onResume of the Activity class.

public class ShakeListener extends Activity

Currently, your class is a subclass of Object class which does not have onResume and onPause method, this is why when you are calling super.onPause and super.onResume, you are getting the exception.