在特定日期在android中設置通知提醒

Question

嗨我想在創建活動時設置提醒通知，但是 我在調用scheduleClient.setAlarmForNotification（c）時收到空指針錯誤。

這是我打電話是錯誤

MainActivity

public class MainActivity extends Activity { 
// This is a handle so that we can call methods on our service 
private ScheduleClient scheduleClient; 
// This is the date picker used to select the date for our notification 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    // Create a new service client and bind our activity to this service 
    scheduleClient = new ScheduleClient(this); 
    scheduleClient.doBindService(); 
    int day =3; 
    int month = 3; 
    int year = 2014; 
    // Create a new calendar set to the date chosen 
    // we set the time to midnight (i.e. the first minute of that day) 
    Calendar c = Calendar.getInstance(); 
    c.set(year, month, day); 
    c.set(Calendar.HOUR_OF_DAY, 0); 
    c.set(Calendar.MINUTE, 0); 
    c.set(Calendar.SECOND, 0); 
    // Ask our service to set an alarm for that date, this activity talks to the client that talks to the service 
    scheduleClient.setAlarmForNotification(c); 
    //Notify the user what they just did 
    Toast.makeText(this, "Notification set for: "+ c.get(Calendar.DAY_OF_MONTH) +"/"+ (month+1) +"/"+ year, Toast.LENGTH_SHORT).show(); 

} 

@Override 
protected void onStop() { 
    // When our activity is stopped ensure we also stop the connection to the service 
    // this stops us leaking our activity into the system *bad* 
    if(scheduleClient != null) 
     scheduleClient.doUnbindService(); 
    super.onStop(); 
} 

}

AlarmTask.java

public class AlarmTask implements Runnable{ 
// The date selected for the alarm 
private final Calendar date; 
// The android system alarm manager 
private final AlarmManager am; 
// Your context to retrieve the alarm manager from 
private final Context context; 

public AlarmTask(Context context, Calendar date) { 
    this.context = context; 
    this.am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); 
    this.date = date; 
} 

@Override 
public void run() { 
    // Request to start are service when the alarm date is upon us 
    // We don't start an activity as we just want to pop up a notification into the system bar not a full activity 
    Intent intent = new Intent(context, NotifyService.class); 
    intent.putExtra(NotifyService.INTENT_NOTIFY, true); 
    PendingIntent pendingIntent = PendingIntent.getService(context, 0, intent, 0); 

    // Sets an alarm - note this alarm will be lost if the phone is turned off and on again 
    am.set(AlarmManager.RTC, date.getTimeInMillis(), pendingIntent); 
} 

}

血清膽鹼酯酶我的主要活動dulecClient

public class ScheduleClient { 

// The hook into our service 
private ScheduleService mBoundService; 
// The context to start the service in 
private Context mContext; 
// A flag if we are connected to the service or not 
private boolean mIsBound; 

public ScheduleClient(Context context) { 
    mContext = context; 
} 

/** 
* Call this to connect your activity to your service 
*/ 
public void doBindService() { 
    // Establish a connection with our service 
    mContext.bindService(new Intent(mContext, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE); 
    mIsBound = true; 
} 

/** 
* When you attempt to connect to the service, this connection will be called with the result. 
* If we have successfully connected we instantiate our service object so that we can call methods on it. 
*/ 
private ServiceConnection mConnection = new ServiceConnection() { 
    public void onServiceConnected(ComponentName className, IBinder service) { 
     // This is called when the connection with our service has been established, 
     // giving us the service object we can use to interact with our service. 
     mBoundService = ((ScheduleService.ServiceBinder) service).getService(); 
    } 

    public void onServiceDisconnected(ComponentName className) { 
     mBoundService = null; 
    } 
}; 

/** 
* Tell our service to set an alarm for the given date 
* @param c a date to set the notification for 
*/ 
public void setAlarmForNotification(Calendar c){ 
    mBoundService.setAlarm(c); 
} 

/** 
* When you have finished with the service call this method to stop it 
* releasing your connection and resources 
*/ 
public void doUnbindService() { 
    if (mIsBound) { 
     // Detach our existing connection. 
     mContext.unbindService(mConnection); 
     mIsBound = false; 
    } 
} 

}

ScheduleService

public class ScheduleService extends Service { 

/** 
* Class for clients to access 
*/ 
public class ServiceBinder extends Binder { 
    ScheduleService getService() { 
     return ScheduleService.this; 
    } 
} 

@Override 
public int onStartCommand(Intent intent, int flags, int startId) { 
    Log.i("ScheduleService", "Received start id " + startId + ": " + intent); 

    // We want this service to continue running until it is explicitly stopped, so return sticky. 
    return START_STICKY; 
} 

@Override 
public IBinder onBind(Intent intent) { 
    return mBinder; 
} 

// This is the object that receives interactions from clients. See 
private final IBinder mBinder = new ServiceBinder(); 

/** 
* Show an alarm for a certain date when the alarm is called it will pop up a notification 
*/ 
public void setAlarm(Calendar c) { 
    // This starts a new thread to set the alarm 
    // You want to push off your tasks onto a new thread to free up the UI to carry on responding 
    new AlarmTask(this, c).run(); 
} 

}

Answer 1

製作一個功能。

public void onDateSelectedClickEvent(View v) { 
    // Get the date from our datepicker 
    int day = 3; 
    int month = 2; 
    int year = 2014; 
    // Create a new calendar set to the date chosen 
    // we set the time to midnight (i.e. the first minute of that day) 
    Calendar c = Calendar.getInstance(); 
    c.set(year, month, day); 
    c.set(Calendar.HOUR_OF_DAY, 0); 
    c.set(Calendar.MINUTE, 0); 
    c.set(Calendar.SECOND, 0); 
    // Ask our service to set an alarm for that date, this activity talks to 
    // the client that talks to the service 
    scheduleClient.setAlarmForNotification(c); 
    // Notify the user what they just did 
    Toast.makeText(
      this, 
      "Notification set for: " + day + "/" + (month + 1) + "/" + year, 
      Toast.LENGTH_SHORT).show(); 
} 

現在在你的xml文件集中調用這個函數你想在xml文件中調用這個事件的按鈕。像

<Button 
    android:id="@+id/sel_btn" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:onClick="onDateSelectedClickEvent" 
    android:text="Notification" /> 

也從onCreate（）方法中刪除該代碼。必須確保您的AndroidManifest.xml文件中註冊了所有服務。