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В настоящее время я делаю приложение для Android с фидом, поэтому я могу отобразить небольшой блог, используя пользовательские данные из QuickBlox. Я хотел, чтобы каждая запись появлялась в CardView с изображением и заголовком под ним, а затем, когда пользователь забирает карту, она расширяется, чтобы отобразить более подробную информацию об этом. Однако мои попытки всегда заканчивались тем, что не отображали карты в RecyclerView. У меня есть данные, которые он загружает, но я не знаю, почему он не появляется.Android Studio: RecyclerView не отображает данные
фрагмент, который содержит основной код HomeRecyclerViewFragment, адаптер CustomAdapter и расположение XML является fragment_home.xml
HomeRecyclerViewFragment:
public class HomeRecyclerViewFragment extends Fragment {
private static final String TAG = "HomeRecyclerViewFragment";
private static final String KEY_LAYOUT_MANAGER = "layoutManager";
private static final int SPAN_COUNT = 2;
private static final int DATASET_COUNT = 60;
private QBCustomObject qbco;
public static ProgressDialog dia;
HashMap<String, Object> fields = new HashMap<String, Object>();
public List<String> ids;
Handler myHandler;
private enum LayoutManagerType {
GRID_LAYOUT_MANAGER,
LINEAR_LAYOUT_MANAGER
}
protected LayoutManagerType mCurrentLayoutManagerType;
protected CardView mLinearLayoutRadioButton;
protected CardView mGridLayoutRadioButton;
protected RecyclerView mRecyclerView;
protected CustomAdapter mAdapter;
protected RecyclerView.LayoutManager mLayoutManager;
protected String[] mDataset;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Initialize dataset, this data would usually come from a local content provider or
// remote server.
dia = ProgressDialog.show(this.getContext(), null,"Downloading recent posts...");
dia.show();
initDataset();
myHandler = new Handler();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_home, container, false);
rootView.setTag(TAG);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.homerecyclerview);
// LinearLayoutManager is used here, this will layout the elements in a similar fashion
// to the way ListView would layout elements. The RecyclerView.LayoutManager defines how
// elements are laid out.
mLayoutManager = new LinearLayoutManager(getActivity());
mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;
if (savedInstanceState != null) {
// Restore saved layout manager type.
mCurrentLayoutManagerType = (LayoutManagerType) savedInstanceState
.getSerializable(KEY_LAYOUT_MANAGER);
}
setRecyclerViewLayoutManager(mCurrentLayoutManagerType);
mAdapter = new CustomAdapter(mDataset);
// Set CustomAdapter as the adapter for RecyclerView.
//mRecyclerView.setAdapter(mAdapter);
mLinearLayoutRadioButton = (CardView) rootView.findViewById(R.id.card_view);
mLinearLayoutRadioButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
setRecyclerViewLayoutManager(LayoutManagerType.LINEAR_LAYOUT_MANAGER);
}
});
//mRecyclerView.setAdapter(mAdapter);
updateUI();
return rootView;
}
/**
* @param layoutManagerType Type of layout manager to switch to.
*/
public void setRecyclerViewLayoutManager(LayoutManagerType layoutManagerType) {
int scrollPosition = 0;
// If a layout manager has already been set, get current scroll position.
if (mRecyclerView.getLayoutManager() != null) {
scrollPosition = ((LinearLayoutManager) mRecyclerView.getLayoutManager())
.findFirstCompletelyVisibleItemPosition();
}
switch (layoutManagerType) {
case GRID_LAYOUT_MANAGER:
mLayoutManager = new GridLayoutManager(getActivity(), SPAN_COUNT);
mCurrentLayoutManagerType = LayoutManagerType.GRID_LAYOUT_MANAGER;
break;
case LINEAR_LAYOUT_MANAGER:
mLayoutManager = new LinearLayoutManager(getActivity());
mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;
break;
default:
mLayoutManager = new LinearLayoutManager(getActivity());
mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;
}
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.scrollToPosition(scrollPosition);
}
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save currently selected layout manager.
savedInstanceState.putSerializable(KEY_LAYOUT_MANAGER, mCurrentLayoutManagerType);
super.onSaveInstanceState(savedInstanceState);
}
private void initDataset() {
QBCustomObjects.getObjects("posts", (QBCallback) qbco, new QBCallbackImpl() {
@Override
public void onComplete(Result result) {
if (result.isSuccess()) {
Log.i(this.toString(),"Retrieved posts successfully.");
dia.dismiss();
QBCustomObjectLimitedResult coresult = (QBCustomObjectLimitedResult) result;
ArrayList<QBCustomObject> co = coresult.getCustomObjects();
int sum = 0;
for (int i = 0; i < co.size(); ++i) {
ids.add(co.get(i).getCustomObjectId());
sum += Arrays.toString(co.toArray()).toCharArray()[i];
}
String[] stockArr = new String[ids.size()];
stockArr = ids.toArray(stockArr);
mDataset = stockArr;
updateUI();
} else {
dia.dismiss();
Log.e("Errors",result.getErrors().toString());
}
}
});
dia.dismiss();
}
private void updateUI() {
mAdapter = new CustomAdapter(mDataset);
mRecyclerView.setAdapter(mAdapter);
}
}
CustomAdapter:
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.MyViewHolder> {
private String[] mDataset;
private Uri[] imgUriList;
private List<String> listOfTitles;
private QBCustomObject qbco;
public ProgressDialog dia;
HashMap<String, Object> fields = new HashMap<String, Object>();
public List<String> ids;
private String id;
private String name;
private String description;
private String year;
private float rating;
private long date;
Handler myHandler;
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public static class MyViewHolder extends RecyclerView.ViewHolder {
public CardView mCardView;
public TextView mTextView;
public MyViewHolder(View v) {
super(v);
mCardView = (CardView) v.findViewById(R.id.card_view);
mTextView = (TextView) v.findViewById(R.id.info_text);
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public CustomAdapter(String[] myDataset) {
mDataset = myDataset;
}
// Create new views (invoked by the layout manager)
@Override
public CustomAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
// create a new view
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.fragment_home, parent, false);
// set the view's size, margins, paddings and layout parameters
MyViewHolder vh = new MyViewHolder(v);
dia = ProgressDialog.show(v.getContext(), null,"Downloading recent posts...");
dia.show();
myHandler = new Handler();
//initQb();
return vh;
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
holder.mTextView.setText(mDataset[position]);
}
@Override
public int getItemCount() {
if (mDataset != null) return mDataset.length;
else return 0;
}
public void initQb() {
QBCustomObjects.getObjects("posts", (QBCallback) qbco, new QBCallbackImpl() {
@Override
public void onComplete(Result result) {
if (result.isSuccess()) {
QBCustomObjectLimitedResult coresult = (QBCustomObjectLimitedResult) result;
ArrayList<QBCustomObject> co = coresult.getCustomObjects();
dia.dismiss();
Log.println(Log.INFO,"PostGetHandler","Retrieved posts successfully.");
int sum = 0;
for (int i = 0; i < co.size(); ++i) {
ids.add(co.get(i).getCustomObjectId().toString());
sum += co.toArray().toString().toCharArray()[i];
}
String[] stockArr = new String[ids.size()];
stockArr = ids.toArray(stockArr);
CustomAdapter ca = new CustomAdapter(stockArr);
} else {
dia.dismiss();
Log.e("Errors",result.getErrors().toString());
}
}
});
}
}
fragment_home.xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="1"
android:id="@+id/linearlayoutv"
xmlns:tools="http://schemas.android.com/tools"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:background="@drawable/splashscreen">
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/homerecyclerview"> </android.support.v7.widget.RecyclerView>
<android.support.v7.widget.CardView
android:id="@+id/card_view"
android:layout_width="match_parent"
card_view:cardCornerRadius="4dp"
android:layout_weight="0.25"
android:layout_height="match_parent"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:layout_marginTop="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="212dp"
android:orientation="horizontal">
<TextView
android:id="@+id/info_text"
android:layout_width="347dp"
android:layout_height="34dp"
android:textSize="16sp"
android:foregroundGravity="bottom"
android:gravity="bottom"
android:layout_marginTop="180dp" />
<ImageView
android:id="@+id/myImage"
android:layout_width="wrap_content"
android:layout_gravity="fill_horizontal"
android:layout_height="wrap_content" />
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
Любая помощь с благодарностью. Благодаря!
Edit 1: Новый журнал ошибок (Прокрутка вправо показывает остальные)
FATAL EXCEPTION: main
Process: com.example.adamangle.ameroboticsapp, PID: 2977
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.CardView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at io.github.adamangle.ameroboticsapp.fragments.HomeRecyclerViewFragment.onCreateView(HomeRecyclerViewFragment.java:105)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2074)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1286)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1671)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:532)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Хорошо, я переместил CardView в другой XML, но он просто разбился (журнал опубликован в Edit 1 для уменьшения помех комментариев) – Cowboy433