谷歌云Messaging.register给出空指针错误 [英] Google cloud Messaging.register gives null pointer error

问题描述

我实现了客户端谷歌云通讯提示错误
这里

I implemented client for Google Cloud Messaging it gives error here

regid = gcm.register(PROJECT_NUMBER); 

是空指针异常

推荐答案

我也对一些客户最近遇到了这个问题，在这里我得到了

i also encountered this problem recently on some clients, where i got

 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.contains(java.lang.CharSequence)' on a null object reference
                                                              at com.google.android.gms.gcm.GoogleCloudMessaging.register(Unknown Source)

终于我可以重现它在一个新的安装程序模拟器中运行API级别23.关键部分是，当我想要注册的发件人ID。

finally i could reproduce it on a fresh setup emulator running api level 23. The critical part is when i want to register the sender id.

    if (gcm == null) {
        gcm = GoogleCloudMessaging.getInstance(context);
    }

    String regId = gcm.register(SENDER_ID);

在GCM对象不为空，但是当你看看在GoogleCloudMessaging.class文件寄存器（）方法，该方法是这样的：

the gcm object is not null, but when you take a look at the register() method of the GoogleCloudMessaging.class file, the method looks like this:

 public synchronized String register(String... senderIds) throws IOException {
    String var2 = this.zzc(senderIds);
    Bundle var3 = new Bundle();
    if(zzaz(this.context).contains(".gsf")) {
        var3.putString("legacy.sender", var2);
        return InstanceID.getInstance(this.context).getToken(var2, "GCM", var3);
    } else {
        var3.putString("sender", var2);
        Intent var4 = this.zzy(var3);
        return zza(var4, "registration_id");
    }
}

在这里似乎空指针来自。载有（）检查。这似乎是如果设备上没有安装谷歌的播放服务的情况。但我不是100％肯定，如果这是主要原因。

and here it seems the nullpointer comes from the .contains() check. this seems to be the case if the google play services are not installed on a device. but i am not 100% sure if that is the main cause.

我最终通过捕捉在gcm.register（）调用的空指针异常，并告诉用户安装谷歌播放服务固定的问题。

i ended up "fixing" the issue by catching the nullpointer exception on the gcm.register() call and telling the user to install the google play services.

此外，register（）方法已经是德precated，所以也许这个问题本身的修补程序切换到使用实例id时：

furthermore the register() method is already deprecated, so maybe this issue fixes itself when switching over to using the InstanceID:

https://developers.google.com/cloud-messaging/registration

https://developers.google.com/instance-id/guides/ Android的实施

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