我真的在任何地方搜索，但却找不到解决这个问题的方法！
所以我正在构建一个倒计时器应用程序。但我面临的问题是，每次计算到00：00.0时，它会等待大约5秒才会发出警报声。如果我碰巧在那段时间点击任何东西它会崩溃应用程序，但是如果我等到它发出警报并重复该过程它将再次等待〜5秒但是这次如果我按下Reset（在那些5秒内或之后）例如，它工作得很好！这是错误：
07-13 14:51:08.838 8808-8808/tech.dronerace.productivitytimer D/AndroidRuntime: Shutting down VM
07-13 14:51:08.838 8808-8808/tech.dronerace.productivitytimer E/AndroidRuntime: FATAL EXCEPTION: main
Process: tech.dronerace.productivitytimer, PID: 8808
java.lang.RuntimeException: Unable to start service tech.dronerace.productivitytimer.Ringtone@11d1fec with Intent { cmp=tech.dronerace.productivitytimer/.Ringtone (has extras) }: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.stop()' on a null object reference
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3027)
at android.app.ActivityThread.-wrap17(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1442)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.stop()' on a null object reference
at tech.dronerace.productivitytimer.Ringtone.onStartCommand(Ringtone.java:52)
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3010)
at android.app.ActivityThread.-wrap17(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1442)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
07-13 14:56:09.149 8808-8808/tech.dronerace.productivitytimer I/Process: Sending signal. PID: 8808 SIG: 9
这是我的方法代码：
public void countDone() {
((Button) findViewById(R.id.b_start)).setVisibility(View.GONE);
((Button) findViewById(R.id.b_reset)).setVisibility(View.VISIBLE);
((Button) findViewById(R.id.b_stop)).setVisibility(View.GONE);
((TextView) findViewById(R.id.timer_id)).setText("00:00");
((TextView) findViewById(R.id.timerMs_id)).setText(".0");
//----------------Alarm && Vibration && Progress----------------\\
final Intent i = new Intent(SecondStep.this, Alarm.class);
i.putExtra("extra", "soundOn");
PendingIntent pi = PendingIntent.getBroadcast(getApplicationContext(), 0, i, PendingIntent.FLAG_UPDATE_CURRENT);
AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
am.setExact(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), pi);
} else {
am.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), pi);
}
Button b = (Button) findViewById(R.id.b_reset);
b.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
updateTimer(startTimeInitialG);
i.putExtra("extra", "soundOff");
PendingIntent.getBroadcast(getApplicationContext(), 0, i, PendingIntent.FLAG_UPDATE_CURRENT);
sendBroadcast(i);
clickReset(v);
((Button) findViewById(R.id.b_start)).setVisibility(View.VISIBLE);
((Button) findViewById(R.id.b_reset)).setVisibility(View.GONE);
}
});
}
现在我选择了Pending Intent，因为我可以通过按下重置按钮来确定音乐已关闭的天气，或者它仍在播放。所以明知它是一个Pending意图我立即启动它以及确切报警（参见上面的代码）以及Update的标志。但似乎没有任何帮助。然后我也从我的自定义构建计时器切换到CountDownTimer类，认为可能存在用于Timer的AlarmManager中的继承错误，但同样的问题再次出现。
为什么要延迟拨打我的闹钟？我究竟做错了什么？ ：P
PS这是我的铃声类（由于错误）。
public class Ringtone extends Service {
MediaPlayer alarmPlayer;
boolean isRunning;
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
//get info on weather the reset was pressed and convert it to int so you can see weather you play or stop the music
String state = intent.getExtras().getString("extra");
assert state != null; //prevents app from crashing
switch (state) {
case "soundOn":
startId = 1;
break;
case "soundOff":
startId = 0;
break;
default:
startId = 0;
break;
}
Log.e("Is the state = 1 or 0?", state);
System.out.println(startId);
//we pressed reset or ('soundOff' ->extra) then cut it off
if(startId == 0 ) {
alarmPlayer.stop();
alarmPlayer.reset();
isRunning = false;
}
//we pressed nothing and is automatically ('soundOn' ->extra) so let it play
else if(startId == 1) {
alarmPlayer = MediaPlayer.create(this, R.raw.imperialmarch);
alarmPlayer.start();
isRunning = true;
}
return START_NOT_STICKY;
}
@Override
public void onDestroy() {
Log.e("On Destroy called..", "yes");
super.onDestroy();
}
}
答案 0 :(得分：0)
为什么要创建PendingIntent并设置一个警报，该警报应该立即关闭以触发BroadcastReciever？您可以自己发送广播Intent，如下所示：
final Intent i = new Intent(SecondStep.this, Alarm.class);
i.putExtra("extra", "soundOn");
sendBroadcast(i);
这会立即触发，您不需要PendingIntent，也不需要警报管理员的参与。