android - Accessing MainActivity once BOOT_COMPLETE is received -

i have reminder app notify me @ given time when next reminder array of objects due.

i trying make set notification again on boot.

i have boot receiver set in manifest, how access information mainactivity once phone has booted, given app hasn't been opened yet?

i hoping use -

public class bootreceiver extends broadcastreceiver {      @override     public void onreceive(context context, intent intent) {         log.i("regularreminders","onreceive");         new mainactivity().setnotifications();     } } 

but returns null error within notification once tries run method in mainactivity, app crashes emulator boots , see in logcat -

java.lang.runtimeexception: unable start receiver com.androidandyuk.regularreminders.bootreceiver: java.lang.nullpointerexception: attempt invoke virtual method 'int java.util.arraylist.size()' on null object reference 

this points line -

if (reminders.size() >= 0) { 

i did wonder if save notification message sharedprefs , call in receiver, got errors of null object reference doing too.

i tried sending broadcast adding info, guess receiver set in mainactivity isn't listening app hasn't been run?

i know google protecting malware, not letting them after book, there way round can set notification after reboot?

thanks.

although can't access variables mainactivity, can access sharedpreferences , sqlite database used in app, in case made new array , read database , worked on that.

wiki