Problem with back button in my app [closed]

Answer 1

How can you clear SharedPreference when the device is switched off.

You can clear it when the device starts thru BraodcastReceiver.

public class PhoneStateReceiver extends BroadcastReceiver{

    @Override
    public void onReceive(final Context context, Intent intent) {

        if(intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)){
            //Clear your `SharedPreference` here.
        }
    }
}

In your manifest add this:

<receiver android:name=".receiver.PhoneStateReceiver">
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED" />
    </intent-filter>
</receiver>  

Add permission:

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

Answer 2

Same question as: Android: Android: How to make a specific SharedPreference reset itself after the system reboots?

I don't know of a different way. This implementation is quite simple. Just handle the BOOT_COMPLETED broadcast action and clear preferences by calling .clear() on the SharedPreference.Editor (answer is here).

A simple Boot receiver might look like this:

public class OnBootReceiver extends BroadcastReceiver{

                @Override
                public void onReceive(Context context, Intent intent) {
                      //clear preferences here         
                }

}

Declare it also in your AndroidManifest.xml as:

           <receiver android:name=".OnBootReceiver">
                    <intent-filter>
                            <action android:name="android.intent.action.BOOT_COMPLETED" />
                    </intent-filter>
            </receiver>

You will also need a permission for this:

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

Answer 3

Asfar as i know the only possibility is to use OnDestroy() but your program should be running when the device is shutdown.