为什么我在我的Android代码中出现空指针错误？

Question

我在我的代码得到一个零点错误和日志在这里指点

199  public void getPurchasedSubs() throws RemoteException { 
200   Bundle ownedItems = mService.getPurchases(3, getPackageName(), "subs", null); 

这里是logcat的文件转储

03-08 13:24:45.619: E/AndroidRuntime(7149): FATAL EXCEPTION: main 
03-08 13:24:45.619: E/AndroidRuntime(7149): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.imobilize.ETV_V3_INAPP_SUB/com.imobilize.ETV_V3_INAPP_SUB.IntroBLevActivity}: java.lang.NullPointerException 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.ActivityThread.access$600(ActivityThread.java:128) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.os.Handler.dispatchMessage(Handler.java:99) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.os.Looper.loop(Looper.java:137) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.ActivityThread.main(ActivityThread.java:4517) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at java.lang.reflect.Method.invokeNative(Native Method) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at java.lang.reflect.Method.invoke(Method.java:511) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:980) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at dalvik.system.NativeStart.main(Native Method) 
03-08 13:24:45.619: E/AndroidRuntime(7149): Caused by: java.lang.NullPointerException 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at com.imobilize.ETV_V3_INAPP_SUB.IntroBLevActivity.getPurchasedSubs(IntroBLevActivity.java:200) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at com.imobilize.ETV_V3_INAPP_SUB.IntroBLevActivity.checkValidation(IntroBLevActivity.java:238) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at com.imobilize.ETV_V3_INAPP_SUB.IntroBLevActivity.onCreate(IntroBLevActivity.java:96) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.Activity.performCreate(Activity.java:4470) 
03-08 13:24:45.619: E/AndroidRuntime(7149):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053) 

SPECS此方法

/** 
* Returns the current SKUs owned by the user of the type and package name specified along with 
* purchase information and a signature of the data to be validated. 
* This will return all SKUs that have been purchased in V3 and managed items purchased using 
* V1 and V2 that have not been consumed. 
* @param apiVersion billing API version that the app is using 
* @param packageName package name of the calling app 
* @param type the type of the in-app items being requested 
*  ("inapp" for one-time purchases and "subs" for subscription). 
* @param continuationToken to be set as null for the first call, if the number of owned 
*  skus are too many, a continuationToken is returned in the response bundle. 
*  This method can be called again with the continuation token to get the next set of 
*  owned skus. 
* @return Bundle containing the following key-value pairs 
*   "RESPONSE_CODE" with int value, RESULT_OK(0) if success, other response codes on 
*    failure as listed above. 
*   "INAPP_PURCHASE_ITEM_LIST" - StringArrayList containing the list of SKUs 
*   "INAPP_PURCHASE_DATA_LIST" - StringArrayList containing the purchase information 
*   "INAPP_DATA_SIGNATURE_LIST"- StringArrayList containing the signatures 
*          of the purchase information 
*   "INAPP_CONTINUATION_TOKEN" - String containing a continuation token for the 
*          next set of in-app purchases. Only set if the 
*          user has more owned skus than the current list. 
*/ 
Bundle getPurchases(int apiVersion, String packageName, String type, String continuationToken); 

当我检查它的包装名称是否有效

她e是创建mService的代码 IInAppBillingService mService;

ServiceConnection mServiceConn = new ServiceConnection() { 
    //@Overide 
     public void onServiceDisconnected(ComponentName name) { 
     mService = null; 
    } 
     //@Overide 
    public void onServiceConnected(ComponentName name, 
     IBinder service) { 
     mService = IInAppBillingService.Stub.asInterface(service); 
    } 

}; 

我不擅长解释logcat文件，所以答案可能就在我面前。

这段代码我认为应该打开它，所以我随时使用mService。

 bindService(new 
      Intent("com.android.vending.billing.InAppBillingService.BIND"), 
        mServiceConn, Context.BIND_AUTO_CREATE); 

Answer 1

我想你在使用mService连接到服务之前。

我的建议是使用布尔变量来检查活动连接服务与否， 或onServiceConnected使用getPurchasedSubs()这样的：

ServiceConnection mServiceConn = new ServiceConnection() { 
    public void onServiceDisconnected(ComponentName name) { 
     mService = null; 
    } 

    public void onServiceConnected(ComponentName name, 
     IBinder service) { 
     mService = IInAppBillingService.Stub.asInterface(service); 
getPurchasedSubs(); 
    } 

}; 

希望这有助于你。