Question

适配器工作正常，直到我决定添加原生广告，因为我在适配器中进行了6次更改。

添加了新的ViewType（AD_VIEW_TYPE）
添加了新的ViewHolder（NativeExpressAdViewHolder）
更改了getItemViewType（使其在每第8个位置返回AD_VIEW_TYPE）

在onCreateViewHolder中添加了一个新案例

     switch (viewType){

        case AD_VIEW_TYPE:
        View nativeExpressLayoutView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.native_express_ad_container, parent, false);
        return new NativeExpressAdViewHolder(nativeExpressLayoutView);

为onBindViewHolder添加了一个新案例

          switch (viewType){

          case AD_VIEW_TYPE:
          NativeExpressAdViewHolder nativeExpressHolder = (NativeExpressAdViewHolder)holder;
          NativeExpressAdView adView = (NativeExpressAdView)arrayList.get(position);

        ViewGroup adCardView = (ViewGroup)nativeExpressHolder.itemView;
        adCardView.removeAllViews();

        if(adView.getParent() != null){
            ((ViewGroup)adView.getParent()).removeView(adView);
        }

        adCardView.addView(adView);
        break;

除了上述更改之外，我还在活动和适配器中将ArrayList<CardSetterGetter>更改为ArrayList<Object>。

现在的问题是，当我运行应用程序时，它会抛出NullPointerException。

logcat说

 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                                                                      at com.company.appname.adapters.RecyclerViewAdapter$RecyclerViewHolder.<init>(RecyclerViewAdapter.java:186)
                                                                      at com.company.appname.adapters.RecyclerViewAdapter$RecyclerViewHolder.<init>(RecyclerViewAdapter.java:165)
                                                                      at com.company.appname.adapters.RecyclerViewAdapter$NativeExpressAdViewHolder.<init>(RecyclerViewAdapter.java:150)
                                                                      at com.company.appname.adapters.RecyclerViewAdapter.onCreateViewHolder(RecyclerViewAdapter.java:84)
                                                                      at com.company.appname.adapters.RecyclerViewAdapter.onCreateViewHolder(RecyclerViewAdapter.java:48)

这些是我的代码中logcat指向

/*Line 48*/public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.RecyclerViewHolder> {
 public RecyclerViewAdapter(Context context, ArrayList<Object> arrayList, ArrayList<String> favouriteItemList, int totalCount {...}

 @Override
 public long getItemId(int position){...}

     @Override
     public RecyclerViewAdapter.RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

         switch (viewType){

         case AD_VIEW_TYPE:
            View nativeExpressLayoutView = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.native_express_ad_container, parent, false);
 /*Line 84*/               return new NativeExpressAdViewHolder(nativeExpressLayoutView); 

         case MENU_ITEM_VIEW_TYPE:

         default:
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cards, parent, false);
            return new RecyclerViewHolder(view);
        }
    }

     @Override
     public void onBindViewHolder(final RecyclerViewHolder holder, final int position){...}

         public class NativeExpressAdViewHolder extends RecyclerViewHolder{
                NativeExpressAdViewHolder(View view){
/*Line 150*/                    super(view);
                }
        }

     @Override
     public int getItemViewType(int position){...}

     @Override
     public int getItemCount(){...}


/*Line 165*/        public class RecyclerViewHolder extends RecyclerView.ViewHolder {

    TextView title;
    RelativeLayout relativeLayout;
    RelativeLayout cardDescription;
    SimpleDraweeView image;
    ImageView favourite_button;
    CardSetterGetter cardSetterGetter;
    ImageView share;


    private RecyclerViewHolder(View itemView) {
        super(itemView);
        title = (TextView) itemView.findViewById(R.id.image_title);
        relativeLayout = (RelativeLayout) itemView.findViewById(R.id.activity_dash_board);
        cardDescription = (RelativeLayout) itemView.findViewById(R.id.card_details);
        image = (SimpleDraweeView) itemView.findViewById(R.id.image);
        favourite_button = (ImageView) itemView.findViewById(R.id.favourite_button);
        share = (ImageView) itemView.findViewById(R.id.share);

 /*Line 186*/           image.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Activity activity = (Activity) context;
                saveInfo(constants.SERVERIP.concat(cardSetterGetter.getImageurl()), cardSetterGetter.getImageId(), cardSetterGetter.getDescription(), cardSetterGetter.getImagetitle(), cardSetterGetter.getFavourite());
                Intent i = new Intent().setClass(context, DetailsImageviewActivity.class);
                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
                context.startActivity(i);
                activity.overridePendingTransition(R.anim.pull_from_right, R.anim.pull_out_to_right);
            }
        });

    }
}
}

我知道NullPointerException是什么，我知道这些问题的解决方案，但在这种情况下，我很难找到问题的来源和解决方案。因此，如果解决方案很简单，请考虑帮助我解决问题，而不是将问题标记为重复。

Answer 1

当在recyclerView中膨胀2种不同的视图类型时，我们需要创建2个单独的ViewHolder类来包含每个布局中的不同元素

尝试以下方法：

//make this a separate class,but not inside the onBindViewHolder
private class NativeExpressAdViewHolder extends RecyclerView.ViewHolder{
    NativeExpressAdViewHolder(View view){                            
    super(view);
    //find the view here
    adView = (NativeExpressAdView)view.findViewById(R.id.native_ad);
}

private class RecyclerViewHolder extends RecyclerView.ViewHolder{
   //this one as usual..
}



//change your onCreateViewHolder for this as well,
// cause now you have 2 view type,so you just override from universal 
//RecyclerView.ViewHolder,not need RecyclerViewAdapter.RecyclerViewHolder
   @Override
     public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { }




@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    int viewType = getItemViewType(position);
    switch (viewType){
      case AD_VIEW_TYPE:
      final NativeExpressAdViewHolder adHolder (NativeExpressAdViewHolder)holder
       //here find your view and load the ad


     break;
     case MENU_ITEM_VIEW_TYPE:
     final  RecyclerViewHolder viewHolder = (RecyclerViewHolder)holder
     //do your thing here,find view,assign value to the layout

    }

还有一件事，请检查您的XML，您的XML应该是这样的

<com.google.android.gms.ads.NativeExpressAdView
        xmlns:ads="http://schemas.android.com/apk/res-auto"
        android:id="@+id/native_ad"
        android:layout_gravity="center_horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        ads:adSize="360x132"
        ads:adUnitId="@string/your_ads">

 </com.google.android.gms.ads.NativeExpressAdView>

RecyclerViewAdapter

1 个答案: