Java Module that communicates JS with Native Android AlarmManager

AlarmManagerModule.js

// Android & Java 
import android.widget.Toast;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.Context;
import java.util.Calendar;

// React
import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;


public class AlarmManagerModule extends ReactContextBaseJavaModule {

  // Constructor
  public AlarmManagerModule(ReactApplicationContext reactContext) {
    super(reactContext);
  }


  @Override
  public String getName() {
    return "AlarmManager";
  }

  @ReactMethod
  public void setAlarm(int hour, int minute) {

       Context context = getReactApplicationContext();

       Intent intent = new Intent(context, AlarmReceiver.class);
       PendingIntent pintent = PendingIntent.getBroadcast(context, 0, intent, 0);

       Calendar calendar = Calendar.getInstance();
       calendar.set(Calendar.HOUR_OF_DAY, hour);
       calendar.set(Calendar.MINUTE, minute);
       calendar.set(Calendar.SECOND, 0);

       AlarmManager alarmManager = (AlarmManager) getReactApplicationContext().getSystemService(Context.ALARM_SERVICE);
       alarmManager.setExact(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pintent);

       Toast.makeText(context, "Alarm set!",Toast.LENGTH_LONG).show();
   }

}

Lot more to add to this. This module will eventually house several different public bridge functions to Javascript that allow for all different types of alarms. Right now this just works off of UTC Wall Clock Time.