Android Alarm Manager Set在特定日期每六个月重复一次

Question

我想每六个月重复一次我的任务。我有以下代码也有这个代码的另一个问题，我想从9/3/2018开始报警，但报警从9/4/2018开始

import java.util.Calendar;
import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;


public class MainActivity extends Activity {



    private AlarmManager AlarmManager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);


        AlarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        Intent intent = new Intent(this, AlarmReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(System.currentTimeMillis());
        calendar.set(Calendar.YEAR, 2018);
        calendar.set(Calendar.MONTH, 3);
        calendar.set(Calendar.DAY_OF_MONTH, 9);

        AlarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),7 * 24 * 60 * 60 * 1000, pendingIntent);

    }
}