IabHelper.startSetup()导致NullPointerException

我的应用程序使用In App Billing,它在我的手机上工作正常(Android 2.3.6).但是当我在模拟器(Android 4.4.2)上运行它时,它会在创建帮助程序以便在应用程序购买中执行时不断崩溃.它抛出一个NullPointerException:

mHelper = new IabHelper(MainActivity.this, base64EncodedPublicKey);
mHelper.startSetup(new IabHelper.OnIabSetupFinishedListener() {
    public void onIabSetupFinished(IabResult result) {
        if (!result.isSuccess()) {
            Log.d("x", "In-app Billing setup failed: " + result);
        } 
        else {             
            Log.d("x", "In-app Billing is set up OK");
        }                             
    }
});

这个答案说我应该将上面的代码放在try-block中,并将catch放在它下面的答案中.这样做时我得到一个错误,推荐的解决方案是将它放在try-catch块中.尽管我这样做了,它仍然会崩溃.

谁能告诉我怎么做？我完全卡住了.

堆栈跟踪:

12-24 10:59:51.908: E/AndroidRuntime(2273): FATAL EXCEPTION: main
12-24 10:59:51.908: E/AndroidRuntime(2273): Process: com.sandradiependaal.mediatie, PID: 2273
12-24 10:59:51.908: E/AndroidRuntime(2273): java.lang.NullPointerException
12-24 10:59:51.908: E/AndroidRuntime(2273):     at com.sandradiependaal.meditatie.util.IabHelper.startSetup(IabHelper.java:267)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at com.sandradiependaal.meditatie.MainActivity$4.onItemClick(MainActivity.java:142)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.widget.AdapterView.performItemClick(AdapterView.java:299)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.widget.AbsListView.performItemClick(AbsListView.java:1113)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:2904)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.widget.AbsListView$3.run(AbsListView.java:3638)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.os.Handler.handleCallback(Handler.java:733)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.os.Handler.dispatchMessage(Handler.java:95)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.os.Looper.loop(Looper.java:136)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at android.app.ActivityThread.main(ActivityThread.java:5017)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at java.lang.reflect.Method.invokeNative(Native Method)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at java.lang.reflect.Method.invoke(Method.java:515)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
12-24 10:59:51.908: E/AndroidRuntime(2273):     at dalvik.system.NativeStart.main(Native Method)

IabHelper.java:

 Intent serviceIntent = new Intent("com.android.vending.billing.InAppBillingService.BIND");
 serviceIntent.setPackage("com.android.vending");
 if (!mContext.getPackageManager().queryIntentServices(serviceIntent, 0).isEmpty()) {
     // service available to handle that Intent
     mContext.bindService(serviceIntent, mServiceConn, Context.BIND_AUTO_CREATE);
 }

user2832636.. 51

这是因为返回的列表不仅仅是空的,而是实际的null.如果列表是,您可以添加一个简单的检查null.为什么实现不返回空列表而不是null我的理解,但它只是它的构建方式.

改为:

List queryIntentServices = mContext.getPackageManager().queryIntentServices(serviceIntent, 0);
if (queryIntentServices != null && !queryIntentServices.isEmpty()) {
        // service available to handle that Intent
        mContext.bindService(serviceIntent, mServiceConn, Context.BIND_AUTO_CREATE);
}

至少这对我来说是模拟器的诀窍.如果正确实现,则在实际设备中不需要这样做.