recyclerview没有适配器;跳过布局

在你的RecyclerView适配器类中，例如MyRecyclerViewAdapter，用下面的参数创建一个构造函数。

MyRecyclerViewAdapter(Context context, List<String> data) {
this.mInflater = LayoutInflater.from(context); // <-- This is the line most people include me miss
this.mData = data;
}

mData是你要传递给适配器的数据。如果没有要传递的数据，则该选项是可选的。 mInflater是你已经创建并在适配器的OnCreateViewHolder函数中使用的LayoutInflater对象

在此之后，您可以将适配器附加到MainActivity或主/UI线程上您想要的任何地方

MyRecyclerViewAdapter recyclerAdapter;
OurDataStuff mData;


....
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);


//Like this:


RecyclerView recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerAdapter = new RecyclerAdapter(this, mData); //this, is the context. mData is the data you want to pass if you have any
recyclerView.setAdapter(recyclerAdapter);
}
....

解决方法是在底部设置初始化的空列表和适配器，并在获取结果时调用notifyDataSetChanged。

    LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
recyclerviewItems.setLayoutManager(linearLayoutManager);
someAdapter = new SomeAdapter(getContext(),feedList);
recyclerviewItems.setAdapter(someAdapter);

首先初始化适配器

public void initializeComments(){
comments = new ArrayList<>();


comments_myRecyclerView = (RecyclerView) findViewById(R.id.comments_recycler);
comments_mLayoutManager = new LinearLayoutManager(myContext);
comments_myRecyclerView.setLayoutManager(comments_mLayoutManager);


updateComments();
getCommentsData();


}


public void updateComments(){


comments_mAdapter = new CommentsAdapter(comments, myContext);
comments_myRecyclerView.setAdapter(comments_mAdapter);
}

当数据集中发生变化时，只需调用updateComments方法。

对于那些在片段中使用RecyclerView并从其他视图扩展它的人:当扩展整个片段视图时，确保你将RecyclerView绑定到它的根视图。

我正在连接和正确地为适配器做一切，但我从未做绑定。 这个回答 by @Prateek阿加瓦尔为我提供了这一切，但这里有更详细的说明

芬兰湾的科特林

    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {


val rootView =  inflater?.inflate(R.layout.fragment_layout, container, false)
recyclerView = rootView?.findViewById(R.id.recycler_view_id)
// rest of my stuff
recyclerView?.setHasFixedSize(true)
recyclerView?.layoutManager = viewManager
recyclerView?.adapter = viewAdapter
// return the root view
return rootView
}

Java

  @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {


View rootView= inflater.inflate(R.layout.fragment_layout,container,false);
recyclerview= rootView.findViewById(R.id.recycler_view_id);
return rootView;
}

我因为这个问题失去了16分钟的生命，所以我要承认这个令人难以置信的尴尬的错误，我正在使用Butterknife，我在这个片段中绑定onCreateView中的视图。

花了很长时间才弄清楚为什么我没有布局管理器-但显然，视图是注入的，所以它们实际上不会为空，所以回收器永远不会为空。哎呀!

@BindView(R.id.recycler_view)
RecyclerView recyclerView;


@Override
public View onCreateView(......) {
View v = ...;
ButterKnife.bind(this, v);
setUpRecycler()
}


public void setUpRecycler(Data data)
if (recyclerView == null) {
/*very silly because this will never happen*/
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
//more setup
//...
}
recyclerView.setAdapter(new XAdapter(data));
}

如果你遇到这样的问题，跟踪你的视图并使用类似uiautomatorviewer的东西

检查是否错过了在适配器中调用此方法

@Override
public int getItemCount() {
return list.size();
}

在我的情况下，它发生了，因为我嵌入了一个RecyclerView在线性布局。

我以前有一个布局文件只包含一个根RecyclerView如下

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.RecyclerView
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:listitem="@layout/fragment_products"


android:name="Products.ProductsFragment"
app:layoutManager="LinearLayoutManager"
tools:context=".Products.ProductsFragment"


xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"/>

我相信问题就在这三行中。不管怎样，我想这是个简单的问题，我明天再来解决。我想我应该在忘记这个帖子之前写下我发现的东西。

只需将以下内容添加到RecyclerView

app:layoutManager="android.support.v7.widget.LinearLayoutManager"

例子:

   <android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"
app:layout_constraintBottom_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">


</android.support.v7.widget.RecyclerView>

添加另一个答案，因为我遇到了这个线程谷歌错误。我试图初始化一个PreferenceFragmentCompat，但我忘记在onCreatePreferences中膨胀首选项XML，就像这样:

class SettingsFragment : PreferenceFragmentCompat() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)


val inflater = LayoutInflater.from(context)
inflater.inflate(R.layout.fragment_settings, null)
}


override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
// Missing this line here:
//   setPreferencesFromResource(R.xml.settings, rootKey)
}
}

这个错误一直是个谜，直到我意识到PreferenceFragmentCompat必须在内部使用RecyclerView。

//当你在创建阶段没有设置适配器时发生:当api response正在获得它的工作时调用notifyDataSetChanged()

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity);




magazineAdapter = new MagazineAdapter(getContext(), null, this );
newClipRecyclerView.setAdapter(magazineAdapter);
magazineAdapter.notifyDataSetChanged();


APICall();
}


public void APICall() {
if(Response.isSuccessfull()){
mRecyclerView.setAdapter(mAdapter);
}
}
Just move setting the adapter into onCreate with an empty data and when you have the data call:


mAdapter.notifyDataSetChanged();

这对我很管用。

1. 如果您正在使用模拟器，请执行此操作。

android: usesCleartextTraffic = " true "

2. 如果你的cardviewxml设计是这样的，

android.support.v7.widget.CardView

androidx.cardview.widget.CardView

3. 如果你的recyclerview xml设计是这样的，

android.support.v7.widget.RecyclerView

androidx.recyclerview.widget.RecyclerView

我得到了同样的问题，我做的每件事都是正确的，除了在xml文件:

• 第一步1:初始化recyclerview &列表,适配器:

  RecyclerView recyclerview;
  List<ModelName> list;
  ProvideBidAdaptor adaptor;
  

• step 2: bind it in onCreate-

  recyclerview = findByViewId(R.id.providerBidRV);
  recyclerview.setLayoutManager(new LinearLayoutManager(this));
  recyclerview.setHasFixedSize(true);
  list = new ArrayList<>();
  

• step 3: Where you getting response or list - add list- (i am getting from response)>

  responseList.addAll(response.getResponse());
  adaptor = new ProvideBidAdaptor(this, responseList);
  binding.detailsRV.setAdapter(adaptor);
  

Here is my xml file where i implement RecyclerView: I was forget orientation in LinearLayout, after this correction- RecyclerView attached.

<?xml version="1.0" encoding="utf-8"?>
<layout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".activities.Bidding.ProvideBid">


<include
android:id="@+id/toolbar"
layout="@layout/app_toolbar"/>


<androidx.recyclerview.widget.RecyclerView
android:id="@+id/providerBidRV"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
</layout>

这是适配器:

    public class ProvideBidAdaptor extends RecyclerView.Adapter<ProvideBidAdaptor.ViewHolder> {
Context context;
List<Response> responseList;
DateTime dateTimeInstance = new DateTime();


public ProvideBidAdaptor(Context context, List<Response> responseList) {
this.context = context;
this.responseList = responseList;
}


@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.geo_presence_item_list, parent, false);
return new ViewHolder(view);
}


@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
final Response detailsResponse = responseList.get(position);
if (!detailsResponse.getUserId().isEmpty()) {


holder.day.setText(detailsResponse.getDay());
holder.locationType.setText(detailsResponse.getLocationType());


}


}


@Override
public int getItemCount() {
return responseList.size();
}


public class ViewHolder extends RecyclerView.ViewHolder {
TextView date,locationType;
CardView provideBidCV;
LinearLayout dayLLayout,locationTypeLLayout;
public ViewHolder(@NonNull View itemView) {
super(itemView);
date = itemView.findViewById(R.id.date_value);
day = itemView.findViewById(R.id.day_value);
locationType = itemView.findViewById(R.id.locationType_value);


locationTypeLLayout = itemView.findViewById(R.id.locationTypeLLayout);


}
}
}

在Kotlin，我们遇到了一个奇怪的不合逻辑的问题。

这并没有起作用:

 mBinding.serviceProviderCertificates.apply {
adapter = adapter
layoutManager =  LinearLayoutManager(activity)
}

虽然这是有效的:

mBinding.serviceProviderCertificates.adapter = adapter
mBinding.serviceProviderCertificates.layoutManager = LinearLayoutManager(activity)

工作之余，我也会分享更多的真知灼见。

只需将代码放入onCreate()方法中

/* Like This*/


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.your_activity);


recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
layoutManager = new LinearLayoutManager(YourActivity.this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setHasFixedSize(true);
mAdapter = new YourAdapter(YourModelClassObject);
recyclerView.setAdapter(mAdapter);
}

我有这个错误，我试着修复了一段时间，直到我找到解决方案。

我做了一个私有方法buildRecyclerView，我调用它两次，第一次在onCreateView，然后在我的回调(其中我从API获取数据)。这是我的方法buildRecyclerView在我的片段:

private void buildRecyclerView(View v) {
mRecyclerView = v.findViewById(R.id.recycler_view_loan);
mLayoutManager = new LinearLayoutManager(getActivity());
((LinearLayoutManager) mLayoutManager).setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new LoanAdapter(mExampleList);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setAdapter(mAdapter);
}

此外，我必须修改我的适配器中的get-Item-Count方法，因为On - On - create - view列表是空的，它通过一个错误。所以，我的get-Item-Count如下所示:

@Override
public int getItemCount() {
try {
return mLoanList.size();
} catch (Exception ex){return 0;}


}

在我的布局xml文件中，缺少了带有layoutManager的底线。我添加后错误消失了。

   <androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view_chat"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:layoutManager="LinearLayoutManager"/>

如果你在使用ViewBinding时得到still错误，请确保你正在使用绑定来返回膨胀的视图

   @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return fragmentBinding.getRoot();
}

 override fun onCreateView(...  ): View?
{
val rootview = inflater.inflate(R.layout.fragment_menu,
container,false)


val recycler_menu_list =
rootview.findViewById(R.id.recycler_menu_list) as RecyclerView


recycler_menu_list.layoutManager = LinearLayoutManager(activity)


val data =  ...


foodCardAdapter = FoodCardAdapter()


recycler_menu_list.adapter=foodCardAdapter


foodCardAdapter.submitList(data)


//make sure that the return view is one declared above up and is
//not the default 'inflater.inflate(R.layout.fragment_menu,
//container,false)' created by the ide


return rootview
}

确保在你的数据绑定或任何你用来显示视图的方法的充气()方法中将attachtorroot属性设置为false:

充气(layoutInflater, parent, false)