java–重复报警不准确

我做了一个应用程序,它有一个数字选择器,范围从1到60分钟,我连接到一个重复的报警管理器.当我试一试时,我注意到它有时候不准确,要么需要更多的工作时间,要么更少.

可能是什么问题呢？

对于开始按钮：

startB.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (startB.isChecked())
{
Calendar calSet = Calendar.getInstance();
calSet.set(Calendar.MINUTE, picker2.getValue());
calSet.set(Calendar.SECOND, 0);
calSet.set(Calendar.MILLISECOND, 0);
setAlarm(calSet);
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putBoolean("toggleButton", startB.isChecked());
editor.commit();
timerHasStarted = true;
}
else
{
Intent intent = new Intent(getBaseContext(), MainReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(getBaseContext(), RQS_1, intent, 0);
AlarmManager alarmManager = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
alarmManager.cancel(pendingIntent);
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putBoolean("toggleButton", startB.isChecked());
editor.commit();
timerHasStarted = false;
}
}
});


对于警报：

private void setAlarm(Calendar targetCal ) {
// TODO Auto-generated method stub
Intent intent = new Intent(getBaseContext(), MainReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(getBaseContext(), RQS_1, intent, 0);
AlarmManager alarmManager = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,
targetCal.getTimeInMillis(),
TimeUnit.MINUTES.toMillis(picker2.getValue()),
pendingIntent);
}


接收器：

@Override
public void onReceive(Context context, Intent intent) {
MediaPlayer m=MediaPlayer.create(context, R.raw.sound);
m.start();
}


解决方法:

Android操作系统能够移动警报,以最大限度地减少唤醒和电池消耗(自API 19起).看看here.我注意到延迟几秒钟.

关于警报的一个非常好的教程可以在here找到