问题
I have made a recyclerview in my app.
The problem is that I'm getting the following error: java.lang.IllegalStateException: RecyclerView has no LayoutManager even when I've defined it.
Here's ListContentAAR.java file's code:
class ListContentAAR {
String picTag;
ListContentAAR( String picTag) {
this.picTag = picTag;
}
}
Here's RVAdapterAAR.java file's code:
public class RVAdapterAAR extends RecyclerView.Adapter<RVAdapterAAR.PersonViewHolder> {
public static class PersonViewHolder extends RecyclerView.ViewHolder {
CardView cardView;
TextView pic;
PersonViewHolder(View itemView) {
super(itemView);
cardView = (CardView) itemView.findViewById(R.id.card_accept_request);
homelessPic = (TextView) itemView.findViewById(R.id.pic_tag);
}
}
List<ListContentAAR> listContentAARs;
RVAdapterAAR(List<ListContentAAR> listContentAARs) {
this.listContentAARs = listContentAARs;
}
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
}
public PersonViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.fragment_accept_a_request, viewGroup, false);
PersonViewHolder personViewHolder = new PersonViewHolder(view);
return personViewHolder;
}
public void onBindViewHolder (PersonViewHolder personViewHolder, int i) {
personViewHolder.pic.setText(listContentAARs.get(i).homelessPicTag);
}
public int getItemCount() {
return listContentAARs.size();
}
}
Here's AcceptARequest.java file's code:
public class AcceptARequest extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
private List<ListContentAAR> listContentAARs;
private RecyclerView recyclerView;
public AcceptARequest() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment AcceptARequest.
*/
// TODO: Rename and change types and number of parameters
public static AcceptARequest newInstance(String param1, String param2) {
AcceptARequest fragment = new AcceptARequest();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_accept_a_request, container, false);
RecyclerView recyclerView = (RecyclerView) rootView.findViewById(R.id.accept_request_list);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.setHasFixedSize(true);
initializeData();
initializeAdapter();
return rootView;
}
private void initializeData(){
listContentAARs = new ArrayList<>();
listContentAARs.add(new ListContentAAR("Emma Wilson"));
}
private void initializeAdapter(){
RVAdapterAAR adapter = new RVAdapterAAR(listContentAARs);
recyclerView.setAdapter(adapter);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
Here's fragment_accept_a_request.xml file's code:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.abc.xyz.AcceptARequest">
<android.support.v7.widget.RecyclerView
android:id="@+id/accept_request_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
<android.support.v7.widget.CardView
android:id="@+id/card_accept_request"
android:layout_width="match_parent"
android:layout_height="@dimen/card_accept_request"
app:cardElevation="2dp"
app:cardUseCompatPadding="true"
app:contentPadding="10dp">
<!--<ImageView
android:id="@+id/pic_accept"
android:layout_width="match_parent"
android:layout_height="@dimen/pic_dimen_accept"
android:layout_gravity="center_horizontal|center_vertical"
android:layout_alignParentTop="true"/> -->
<TextView
android:id="@+id/pic_tag"
android:layout_width="match_parent"
android:layout_height="@dimen/pic_dimen_accept"
android:text="@string/image_view_tag_accept"
android:gravity="center_horizontal|center_vertical"/>
</android.support.v7.widget.CardView>
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
Here's MainActivity.java file's code:
public class MainActivity extends AppCompatActivity {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
public SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Typeface typeFace = Typeface.createFromAsset(getAssets(),"fonts/Pacifico.ttf");
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
TextView mTitle = (TextView) toolbar.findViewById(R.id.toolbar_title);
mTitle.setTypeface(typeFace);
toolbar.setTitle(mTitle.getText().toString());
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
/*FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});*/
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
Intent settingsIntent = new Intent(MainActivity.this, SettingsActivity.class);
startActivity(settingsIntent);
} else if (id == R.id.action_profile) {
Intent profileIntent = new Intent(MainActivity.this, ProfileActivity.class);
startActivity(profileIntent);
} else if (id == R.id.action_send_feedback) {
Intent sendFeedbackIntent = new Intent(MainActivity.this, SendFeedback.class);
startActivity(sendFeedbackIntent);
} else if (id == R.id.action_help) {
Intent helpIntent = new Intent(MainActivity.this, HelpActivity.class);
startActivity(helpIntent);
}
return super.onOptionsItemSelected(item);
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
protected Context mContext;
public SectionsPagerAdapter(Context context, FragmentManager fm) {
super(fm);
mContext = context;
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
// return MainActivity.PlaceholderFragment.newInstance(position + 1);
switch (position) {
case 0:
return new AcceptARequest();
case 1:
return new PostARequest();
default:
return new AcceptARequest(); // return AcceptARequest() actually
}
}
@Override
public int getCount() {
// Show 2 total pages.
return 2;
}
@Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return "Accept A Request";
case 1:
return "Post A Request";
}
return null;
}
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.section_label);
textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
}
Here's the stacktrace:
FATAL EXCEPTION: main
java.lang.IllegalStateException: RecyclerView has no LayoutManager
at android.support.v7.widget.RecyclerView.generateLayoutParams(RecyclerView.java:3182)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:748)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:749)
at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
at com.humanehelper.humanehelper.AcceptARequest.onCreateView(AcceptARequest.java:75)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1106)
at android.support.v4.view.ViewPager.populate(ViewPager.java:952)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:610)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:677)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
at android.view.View.measure(View.java:15172)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com
As I'm a beginner, I'm unable to figure out why am I getting the following error.
Please let me know.
Thanks in advance.
回答1:
Remove the child elements from your RecyclerView in your fragment_accept_a_request layout.
You add children to your recycler views with the adapter, not via nested XML elements.
The problem is that when the layout inflation tries to add those children you've declared in your XML the parent RecyclerView is not yet fully configured to have children.
回答2:
I got it!
The problem was in two files.
First problem as stated by laalto was in fragment_accept_a_request.xml. Removing the XML elements from recyclerView & placing it below it but in the same parent layout did the job.
Second problem was in AcceptARequest.java. Here I was declaring two RecyclerView one for initialiseData() method & another for declaring the recyclerView.
The changes I made in fragment_accept_a_request.xml is:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="com.abc.xyz.AcceptARequest">
<android.support.v7.widget.RecyclerView
android:id="@+id/accept_request_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
</android.support.v7.widget.RecyclerView>
<android.support.v7.widget.CardView
android:id="@+id/card_accept_request"
android:layout_width="match_parent"
android:layout_height="@dimen/card_accept_request"
app:cardElevation="2dp"
app:cardUseCompatPadding="true"
app:contentPadding="10dp">
<!--<ImageView
android:id="@+id/pic_accept"
android:layout_width="match_parent"
android:layout_height="@dimen/pic_dimen_accept"
android:layout_gravity="center_horizontal|center_vertical"
android:layout_alignParentTop="true"/> -->
<TextView
android:id="@+id/pic_tag"
android:layout_width="match_parent"
android:layout_height="@dimen/pic_dimen_accept"
android:text="@string/image_view_tag_accept"
android:gravity="center_horizontal|center_vertical"/>
</android.support.v7.widget.CardView>
</RelativeLayout>
来源：https://stackoverflow.com/questions/33969443/why-is-it-saying-recyclerview-has-no-layoutmanager-when-there-is-one-please-s