我正在使用此查询来获取数据：
query Products($id: ID!){
node(id: $id) {
id
... on Collection {
title
products(first: 250){
edges{
node{
title
id
variants(first: 1){
edges{
node{
price
}
}
}
images(first: 1,maxWidth:400,maxHeight:740,scale:3){
edges{
node{
src
}
}
}
}
}
}
}
}
}
在ApolloCall.CallBack的OnResponse方法中，当我想要获取产品标题时，它会在此行生成nullPointerException＆＃34; Log.i（＆＃34; CallBack products＆＃34;，String.valueOf（response.data（）。node（）。asCollection（）。products（）。edges（）））; ＆＃34; 我需要在recyclerview中显示产品的标题，价格和图像。获取它们的最佳方法是什么？ 提前谢谢！
下面是我的代码：
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_product);
String s = getIntent().getStringExtra("id");
Bundle extras = getIntent().getExtras();
if (extras != null) {
s = extras.getString("id");
}
application = (SampleApplication) getApplication();
content = (ViewGroup) findViewById(R.id.rl_content_holder);
progressBar = (ProgressBar) findViewById(R.id.loading_bar);
productRecyclerView = (RecyclerView) findViewById(R.id.rvProductList);
mProductAdapter = new ProductAdapter(this);
mGridLayoutManager = new GridLayoutManager(this,2);
fetchProducts();
}
ApolloCall.Callback<Products.Data> mDataCallback =
new ApolloCall.Callback<Products.Data>() {
@Override
public void onResponse(@Nonnull final Response<Products.Data> response) {
Log.i("CallBack products", String.valueOf(response.data().node().asCollection().products().edges()));
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(ProductActivity.this, "getting products", Toast.LENGTH_SHORT).show();
mProductAdapter.setProductData(response.data().node().asCollection().products().edges());
productRecyclerView.setAdapter(mProductAdapter);
productRecyclerView.setLayoutManager(mGridLayoutManager);
progressBar.setVisibility(View.GONE);
content.setVisibility(View.VISIBLE);
}
});
}
@Override
public void onFailure(@Nonnull ApolloException e) {
Log.e("Product Activity", e.getMessage(), e);
runOnUiThread(new Runnable() {
@Override
public void run() {
progressBar.setVisibility(View.GONE);
Toast.makeText(ProductActivity.this, "getting products failed", Toast.LENGTH_SHORT).show();
}
});
}
};
public void fetchProducts() {
mHttpClient = new OkHttpClient.Builder()
.addInterceptor(new HttpInterceptor())
.build();
Products productQuery = Products
.builder().id("id")
.build();
productCall = application.apolloClient().newCall(productQuery);
productCall.enqueue(mDataCallback);
}
这里是RecyclerView适配器：
public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ViewHolder> {
// Store the context for easy access
private Context mContext;
private List<Products.Data.Edge> productData = Collections.emptyList();
public void setProductData(List<Products.Data.Edge>productData) {
this.productData = productData;
this.notifyDataSetChanged();
}
public ProductAdapter(Context context ) {
mContext = context;
}
private Context getContext() {
return mContext;
}
public static class ViewHolder extends RecyclerView.ViewHolder {
public TextView productListItem;
public ImageView productListImage;
private View rlContainer;
Context context;
public ViewHolder(Context context,View itemView) {
super(itemView);
productListItem = (TextView) itemView.findViewById(R.id.itemProductTxt);
productListImage = (ImageView)itemView.findViewById(R.id.itemProductImg);
rlContainer = itemView.findViewById(R.id.linear_layout);
this.context = context;
}
public void setProductItem(final Products.Data.Edge productItem) {
productListItem.setText(productItem.node().title());
rlContainer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(context, "list item pressed", Toast.LENGTH_SHORT).show();
}
});
}
}
@Override
public ProductAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
// Inflate the custom layout
View productView = inflater.inflate(R.layout.listitem_product, parent, false);
// Return a new holder instance
ProductAdapter.ViewHolder viewHolder = new ProductAdapter.ViewHolder(context,productView);
return viewHolder;
}
@Override
public void onBindViewHolder(ProductAdapter.ViewHolder holder, int position) {
final Products.Data.Edge productsEntry = this.productData.get(position);
holder.setProductItem(productsEntry);
@Override
public int getItemCount() {
return productData.size();
}
}
答案 0 :(得分：0)
请你提供堆栈跟踪。 你确定你没有回复空洞吗？
你得到NPE可能是因为id所请求的节点不存在。