App crashes on received gcm message when it's closed

问题

When my app is closed (i.e swiped off by the user from the App Switching menu), it crashes in onMessageReceived().

Here's onMessageReceived():

@Override
public void onMessageReceived(String from, Bundle data) {
    String message = data.getString("message");
    from = data.getString("sender");

    File notificationsFile = Constants.getNotificationsFlagFile();
    ...
}

It crashes on that last line, giving a null pointer exception:

08-13 21:15:25.535 23201-23216/com.example.myapp E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1 java.lang.ExceptionInInitializerError at com.example.myapp.chatGCM.MyGcmListenerService.onMessageReceived(MyGcmListenerService.java:52) at com.google.android.gms.gcm.GcmListenerService.zzs(Unknown Source) at com.google.android.gms.gcm.GcmListenerService.zzk(Unknown Source) at com.google.android.gms.gcm.GcmListenerService.zza(Unknown Source) at com.google.android.gms.gcm.GcmListenerService$1.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) at java.lang.Thread.run(Thread.java:841) Caused by: java.lang.NullPointerException at helpers.Constants.(Constants.java:54) at com.example.myapp.chatGCM.MyGcmListenerService.onMessageReceived(MyGcmListenerService.java:52) at com.google.android.gms.gcm.GcmListenerService.zzs(Unknown Source) at com.google.android.gms.gcm.GcmListenerService.zzk(Unknown Source) at com.google.android.gms.gcm.GcmListenerService.zza(Unknown Source) at com.google.android.gms.gcm.GcmListenerService$1.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) at java.lang.Thread.run(Thread.java:841)

and here's getNotificationsFlagFile():

public static File getNotificationsFlagFile()
{
    return new File(MainApplication.getAppContext().getFilesDir(), "notifications_"+getSession());
}

and finally:

private static String getSession()
{
    File file = new File(MainApplication.getAppContext().getFilesDir(), "session");
    int length = (int) file.length();
    byte[] bytes = new byte[length];
    FileInputStream in = null;
    try {
        in = new FileInputStream(file);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    try {
        try {
            in.read(bytes);
        } catch (IOException e) {
            e.printStackTrace();
        }
    } finally {
        try {
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return (new String(bytes));
}

All I'm using is static variables and functions. Why is this happening?

回答1:

From here you seem to be having an un-expected behavior... Probably from the getAppContext() function... try using getApplicationContext() instead.

来源：https://stackoverflow.com/questions/31995818/app-crashes-on-received-gcm-message-when-its-closed

标签

android

android-asynctask

google-cloud-messaging