我有一个闹钟，每天都会在特定的时间触发。我已经测试了射击效果。
现在，当警报响起时，我想打电话给你 updateTextView() 从 MainActivity ，它改变了 TextView 在 activity_main.xml . 我在这里尝试了许多解决方法：要么我不理解，要么它们不起作用。
主要活动：

public class MainActivity extends AppCompatActivity {
    public TextView dailyTextView;
    //TESTING
    private static final String TAG = "MyActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        dailyTextView = findViewById(R.id.main_text);
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(System.currentTimeMillis());
        calendar.set(Calendar.HOUR_OF_DAY, 13);
        calendar.set(Calendar.MINUTE,25);
        startAlarm(calendar);
    }
    public void updateTextView() {
        ...
    }
    private void startAlarm(Calendar calendar) {
        Toast.makeText(this,"ALARM TEST",Toast.LENGTH_LONG).show();
        AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        Intent intent = new Intent(this, DailyUpdateReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this,1, intent,0);
        alarmManager.setExact(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
    }
}

广播接收器：

public class DailyUpdateReceiver extends BroadcastReceiver {
    private static final String TAG = "MyActivity";
    //TODO: WORK ON THIS
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i(TAG, "ON RECEIVE STARTED!!!!!!!!!!!!!!!!!!!!!!");
    }
}