java - 回收站视图在片段中为空
问题描述
我正在尝试解析 JSON 数据并使用RecyclerView
. 但是,当我运行该应用程序时,我得到一个空白屏幕。我第一次使用Activity
完美运行的代码完成了这段代码。然后我将其转换为Fragment
. 在Fragment
它显示一个空白屏幕。
这是我的代码Fragment
public class Tab1 extends Fragment {
private RecyclerView mRecyclerView;
private ExampleAdapter mExampleAdapter;
private ArrayList<ExampleItem> mExampleList;
private RequestQueue mRequestQueue;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.tab1, container, false);
mRecyclerView = rootView.findViewById(R.id.recycler_view);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false));
mExampleList = new ArrayList<>();
mRequestQueue = Volley.newRequestQueue(requireActivity());
parseJson();
return rootView;
}
private void parseJson(){
String url ="http://maranamassapp.cf/json_getdata.php";
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("server_response");
for(int i = 0; i < jsonArray.length(); i++){
JSONObject ser =jsonArray.getJSONObject(i);
String creatorname = ser.getString("filmname");
String imageUrl = ser.getString("filmimage");
String cat = ser.getString("filmcat");
mExampleList.add(new ExampleItem(imageUrl,creatorname,cat));
}
mExampleAdapter = new ExampleAdapter(getContext(),mExampleList);
mRecyclerView.setAdapter(mExampleAdapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
mRequestQueue.add(request);
}
}
和适配器代码
public class ExampleAdapter extends RecyclerView.Adapter <ExampleAdapter.ExampleViewHolder>{
private Context mContext;
private ArrayList<ExampleItem> mExampleList;
public ExampleAdapter(Context context, ArrayList<ExampleItem> examplelist){
mContext =context;
mExampleList = examplelist;
}
@NonNull
@Override
public ExampleViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(mContext).inflate(R.layout.example_item,parent,false);
return new ExampleViewHolder(v);
}
@Override
public void onBindViewHolder(@NonNull ExampleViewHolder holder, int position) {
ExampleItem currentItem = mExampleList.get(position);
String imageUrl = currentItem.getmImageUrl();
String creatorName = currentItem.getmCreator();
String cat =currentItem.getmCat();
holder.mTextViewCreator.setText(creatorName);
holder.mTextViewCat.setText(cat);
Glide.with(mContext)
.load(imageUrl)
.into(holder.mImageView);
}
@Override
public int getItemCount() {
return mExampleList.size();
}
public class ExampleViewHolder extends RecyclerView.ViewHolder{
public ImageView mImageView;
public TextView mTextViewCreator;
public TextView mTextViewCat;
public ExampleViewHolder(View itemView) {
super(itemView);
mImageView = itemView.findViewById(R.id.image_view);
mTextViewCreator = itemView.findViewById(R.id.text_view_creator);
mTextViewCat = itemView.findViewById(R.id.text_view_cat);
}
}
}
有人可以帮忙吗?
解决方案
我建议您执行以下RecyclerView
类似操作。
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.tab1, container, false);
mRecyclerView = rootView.findViewById(R.id.recycler_view);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false));
mExampleList = new ArrayList<>();
mRequestQueue = Volley.newRequestQueue(requireActivity());
// Set the adapter here.
// Use getActivity() instead of getContext()
mExampleAdapter = new ExampleAdapter(getContext(),mExampleList);
parseJson();
return rootView;
}
private void parseJson(){
String url ="http://maranamassapp.cf/json_getdata.php";
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("server_response");
for(int i = 0; i < jsonArray.length(); i++){
JSONObject ser =jsonArray.getJSONObject(i);
String creatorname = ser.getString("filmname");
String imageUrl = ser.getString("filmimage");
String cat = ser.getString("filmcat");
mExampleList.add(new ExampleItem(imageUrl,creatorname,cat));
}
// Just call notifyDataSetChanged here
mExampleAdapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
mRequestQueue.add(request);
}
请注意,我将onCreateView
传递的适配器设置getActivity()
为上下文而不是getContext
. 在parseJson
函数中,我只是notifyDataSetChanged
在mExampleList
使用新添加的数据更新时调用。
此外,请检查您是否正确地从服务器获得响应,并且在解析响应时您没有收到任何异常。
希望这有效!
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