java - Android 通知设置期间 Toast 消息显示两次

Question

我在 Android 应用程序中有一个选项可以设置两个通知。基本上，当用户单击按钮时，会显示一个时间选择器，第一次时间选择器完成后，会弹出第二个时间选择器，供用户第二次插入。

两个时间选择器都采用单独的方法，在第一个方法结束时会显示一个 toast，与第二个方法相同。问题是，当第一次选择器完成两个 toast 消息时立即触发，然后当用户完成第二次选择器时，第二个 toast 消息再次触发。我已包含以下代码。

 /**
 * Method which sets the first daily notification
 */
private void startTwiceDailyNotification(Calendar c) {
    DialogFragment timePicker = new TimePickerFragment();
    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(this, AlertReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 1, intent, 0);

    alarmManager.setExact(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pendingIntent);
    alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);
    Toast.makeText(this, "First Notification Set.", Toast.LENGTH_SHORT).show();
    timePicker.show(getSupportFragmentManager(), "time picker4");
    hasSelected = 2;

}

/**
 * Method which sets the second daily notification
 */
private void startTwiceDailyNotification2(Calendar c) {
    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(this, AlertReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 2, intent, 0);

    alarmManager.setExact(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pendingIntent);
    alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);
    Toast.makeText(this, "Second Notification Set.", Toast.LENGTH_SHORT).show();

}




 @Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

    calendar.set(Calendar.HOUR_OF_DAY, hourOfDay);
    calendar.set(Calendar.MINUTE, minute);
    calendar.set(Calendar.SECOND, 0);

    if (hasSelected == 1) {
        startTwiceDailyNotification(calendar);
    }

    if (hasSelected == 2) {
        startTwiceDailyNotification2(calendar);
    }
}

Answer 1

就像你可以在这个answer.中读到的那样:

When you write multiple if statements, it's possible that more than one of them will be evaluated to true, since the statements are independent of each other.

When you write a single if else-if else-if ... else statement, only one condition can be evaluated to true (once the first condition that evaluates to true is found, the next else-if conditions are skipped).

因此，在方法startTwiceDailyNotification之后的示例中，变量hasSelected设置为2。因此第二个“if语句”被评估为true，这就是方法的原因>startTwiceDailyNotification2 被调用。

要修复它，您应该使用“单个 if else-if else-if ... else 语句”，如下所示:

@Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

    calendar.set(Calendar.HOUR_OF_DAY, hourOfDay);
    calendar.set(Calendar.MINUTE, minute);
    calendar.set(Calendar.SECOND, 0);

    if (hasSelected == 1) {
        startTwiceDailyNotification(calendar);
    } 
    else if (hasSelected == 2) {
        startTwiceDailyNotification2(calendar);
    }
}