Recyclerview實現中Admob NativeExpressAdView的問題

Question

我在這裏問這個問題之前已經做了大量的搜索。

我在我的Recyclerview中集成了NativeExpressAdView，如此處google example中所述，它也工作正常。但問題是，在這個示例項目中，他們從第零個位置添加NativeExpressAdView，但不想在第零個位置添加NativeExpressAdView。

我也可以隨機添加位置，但是當我們必須從代碼設置NativeExpressAdView的廣告大小時，就會出現問題。

Cardview，在MainActivity的setUpAndLoadNativeExpressAds方法中訪問，將爲空，並且如果不在第零位添加視圖，則將給予NPE。

這是我修改後的代碼片斷

/** 
    * Adds Native Express ads to the items list. 
    */ 
    private void addNativeExpressAds() { 

     // Loop through the items array and place a new Native Express ad in every ith position in 
     // the items List. 
     for (int i = 7; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) { 
      final NativeExpressAdView adView = new NativeExpressAdView(MainActivity.this); 
      mRecyclerViewItems.add(i, adView); 
     } 
    } 

    /** 
    * Sets up and loads the Native Express ads. 
    */ 
    private void setUpAndLoadNativeExpressAds() { 
     // Use a Runnable to ensure that the RecyclerView has been laid out before setting the 
     // ad size for the Native Express ad. This allows us to set the Native Express ad's 
     // width to match the full width of the RecyclerView. 
     mRecyclerView.post(new Runnable() { 
      @Override 
      public void run() { 
       final float scale = MainActivity.this.getResources().getDisplayMetrics().density; 
       // Set the ad size and ad unit ID for each Native Express ad in the items list. 
       for (int i = 7; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) { 
        final NativeExpressAdView adView = 
          (NativeExpressAdView) mRecyclerViewItems.get(i); 
        final CardView cardView = (CardView) findViewById(R.id.ad_card_view); 
        final int adWidth = cardView.getWidth() - cardView.getPaddingLeft() 
          - cardView.getPaddingRight(); //Here cardView will be Null (so NPE). 
        AdSize adSize = new AdSize((int) (adWidth/scale), NATIVE_EXPRESS_AD_HEIGHT); 
        adView.setAdSize(adSize); 
        adView.setAdUnitId(AD_UNIT_ID); 
       } 

       // Load the first Native Express ad in the items list. 
       loadNativeExpressAd(7); //Not added code for this method as nothing is modified in that. 
      } 
     }); 
    } 

即使我從回購拉動示例項目代碼後執行同樣的變化這個問題來了。

這裏是我的logcat崩潰

FATAL EXCEPTION: main 
java.lang.NullPointerException                               at com.google.android.gms.example.nativeexpressrecyclerviewexample.MainActivity$1.run(MainActivity.java:106) 
at android.os.Handler.handleCallback(Handler.java:725) 
at android.os.Handler.dispatchMessage(Handler.java:92) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:5041) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
at dalvik.system.NativeStart.main(Native Method) 

因此，這是某種錯誤的或我在做什麼錯。

Answer 1

只是增加一個條件，即

if (i!=0){} 

在

都爲循環
更新：

*/ 
private void addNativeExpressAds() { 

    // Loop through the items array and place a new Native Express ad in every ith position in 
    // the items List. 
    for (int i = 0; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) { 
if(i!=0){ 
     final NativeExpressAdView adView = new NativeExpressAdView(MainActivity.this); 
     mRecyclerViewItems.add(i, adView); 
    }} 
} 

/** 
* Sets up and loads the Native Express ads. 
*/ 
private void setUpAndLoadNativeExpressAds() { 
    // Use a Runnable to ensure that the RecyclerView has been laid out before setting the 
    // ad size for the Native Express ad. This allows us to set the Native Express ad's 
    // width to match the full width of the RecyclerView. 
    mRecyclerView.post(new Runnable() { 
     @Override 
     public void run() { 
      final float scale = MainActivity.this.getResources().getDisplayMetrics().density; 
      // Set the ad size and ad unit ID for each Native Express ad in the items list. 
      for (int i = 0; i <= mRecyclerViewItems.size(); i += ITEMS_PER_AD) { 
if(i!=0){ 
       final NativeExpressAdView adView = 
         (NativeExpressAdView) mRecyclerViewItems.get(i); 
       final CardView cardView = (CardView) findViewById(R.id.ad_card_view); 
       final int adWidth = cardView.getWidth() - cardView.getPaddingLeft() 
         - cardView.getPaddingRight(); //Here cardView will be Null (so NPE). 
       AdSize adSize = new AdSize((int) (adWidth/scale), NATIVE_EXPRESS_AD_HEIGHT); 
       adView.setAdSize(adSize); 
       adView.setAdUnitId(AD_UNIT_ID); 
      }} 

      // Load the first Native Express ad in the items list. 
      loadNativeExpressAd(ITEMS_PER_AD); //Not added code for this method as nothing is modified in that. 
     } 
    }); 
}