java购买。getsku（）是否返回null？

Question

我只想检查用户的购买是否与"donate_one_dollar"的SKU匹配。但是我得到了一个错误：

    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String util.Purchase.getSku()' on a null object reference

at com.curlybrace.ruchir.rescuer.MainActivity$13.onIabPurchaseFinished(MainActivity.java:1113)
at util.IabHelper.launchPurchaseFlow(IabHelper.java:472)
at util.IabHelper.launchPurchaseFlow(IabHelper.java:398)
at util.IabHelper.launchPurchaseFlow(IabHelper.java:392)

基本上，mPurchaseFinishedListener似乎返回一个空的purchase对象。我该怎么解决这个问题

---

IabHelper.OnIabPurchaseFinishedListener mPurchaseFinishedListener
            = new IabHelper.OnIabPurchaseFinishedListener() {
        public void onIabPurchaseFinished(IabResult result, Purchase purchase) {

            Log.v("myTag", "Purchase finished. SKU = " +purchase.getSku()); //NOT WORKING

                if (purchase.getSku().equals("donate_one_dollar")) { **//DOESNT WORK**

                    Toast.makeText(MainActivity.this, "One dollar donated!", Toast.LENGTH_SHORT).show();
                }
        }
    };

我正在使用测试账户的Beta测试来测试我的购买