如何用RecyclerView显示一个空视图?

我习惯于将布局文件中的特殊视图在ListActivity文档中描述改为无数据时显示。这个视图的id为"android:id/empty"。

<TextView
android:id="@android:id/empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/no_data" />

我想知道如何使用新的RecyclerView?

220815 次浏览
小开

在适配器的getItemViewType上检查适配器是否有0个元素，如果是，则返回不同的viewType。

然后在你的onCreateViewHolder上检查viewType是否是你之前返回的那个，并膨胀一个不同的视图。在这种情况下，布局文件与该TextView

编辑

如果这仍然不能工作，那么你可能想通过编程来设置视图的大小，就像这样:

Point size = new Point();
((WindowManager)itemView.getContext().getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getSize(size);

然后当你膨胀你的视图调用:

inflatedView.getLayoutParams().height = size.y;
inflatedView.getLayoutParams().width = size.x;
小开
最佳答案

在定义RecyclerView的相同布局中，添加TextView:

<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical" />


<TextView
android:id="@+id/empty_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:visibility="gone"
android:text="@string/no_data_available" />
在onCreate或适当的回调中，您检查提供RecyclerView的数据集是否为空。 如果数据集是空的，RecyclerView也是空的。在这种情况下，消息将显示在屏幕上。 如果不是，改变它的可见性:

private RecyclerView recyclerView;
private TextView emptyView;


// ...


recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
emptyView = (TextView) rootView.findViewById(R.id.empty_view);


// ...


if (dataset.isEmpty()) {
recyclerView.setVisibility(View.GONE);
emptyView.setVisibility(View.VISIBLE);
}
else {
recyclerView.setVisibility(View.VISIBLE);
emptyView.setVisibility(View.GONE);
}
小开

对于我的项目，我做了这个解决方案(RecyclerView与setEmptyView方法):

public class RecyclerViewEmptySupport extends RecyclerView {
private View emptyView;


private AdapterDataObserver emptyObserver = new AdapterDataObserver() {




@Override
public void onChanged() {
Adapter<?> adapter =  getAdapter();
if(adapter != null && emptyView != null) {
if(adapter.getItemCount() == 0) {
emptyView.setVisibility(View.VISIBLE);
RecyclerViewEmptySupport.this.setVisibility(View.GONE);
}
else {
emptyView.setVisibility(View.GONE);
RecyclerViewEmptySupport.this.setVisibility(View.VISIBLE);
}
}


}
};


public RecyclerViewEmptySupport(Context context) {
super(context);
}


public RecyclerViewEmptySupport(Context context, AttributeSet attrs) {
super(context, attrs);
}


public RecyclerViewEmptySupport(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}


@Override
public void setAdapter(Adapter adapter) {
super.setAdapter(adapter);


if(adapter != null) {
adapter.registerAdapterDataObserver(emptyObserver);
}


emptyObserver.onChanged();
}


public void setEmptyView(View emptyView) {
this.emptyView = emptyView;
}
}

你应该使用它来代替RecyclerView类:

<com.maff.utils.RecyclerViewEmptySupport android:id="@+id/list1"
android:layout_height="match_parent"
android:layout_width="match_parent"
/>


<TextView android:id="@+id/list_empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Empty"
/>

而且

RecyclerViewEmptySupport list =
(RecyclerViewEmptySupport)rootView.findViewById(R.id.list1);
list.setLayoutManager(new LinearLayoutManager(context));
list.setEmptyView(rootView.findViewById(R.id.list_empty));
小开

我使用ViewSwitcher

<ViewSwitcher
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/switcher"
>


<android.support.v7.widget.RecyclerView
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>


<TextView android:id="@+id/text_empty"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="@string/list_empty"
android:gravity="center"
/>


</ViewSwitcher>

在代码中，您将检查光标/数据集和切换视图。

void showItems(Cursor items) {
if (items.size() > 0) {


mAdapter.switchCursor(items);


if (R.id.list == mListSwitcher.getNextView().getId()) {
mListSwitcher.showNext();
}
} else if (R.id.text_empty == mListSwitcher.getNextView().getId()) {
mListSwitcher.showNext();
}
}

如果你愿意，你也可以用几行代码设置动画

mListSwitcher.setInAnimation(slide_in_left);
mListSwitcher.setOutAnimation(slide_out_right);
小开

我在RelativeLayout中添加了RecyclerView和替代ImageView:

<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">


<ImageView
android:id="@+id/no_active_jobs"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@mipmap/ic_active_jobs" />


<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />


</RelativeLayout>

然后在Adapter中:

@Override
public int getItemCount() {
if (mOrders.size() == 0) {
mRecyclerView.setVisibility(View.INVISIBLE);
} else {
mRecyclerView.setVisibility(View.VISIBLE);
}
return mOrders.size();
}
小开

下面是一种解决方案，它仅使用一个自定义适配器，为空情况使用不同的视图类型。

public class EventAdapter extends
RecyclerView.Adapter<EventAdapter.ViewHolder> {


private static final int VIEW_TYPE_EVENT = 0;
private static final int VIEW_TYPE_DATE = 1;
private static final int VIEW_TYPE_EMPTY = 2;


private ArrayList items;


public EventAdapter(ArrayList items) {
this.items = items;
}


@Override
public int getItemCount() {
if(items.size() == 0){
return 1;
}else {
return items.size();
}
}


@Override
public int getItemViewType(int position) {
if (items.size() == 0) {
return VIEW_TYPE_EMPTY;
}else{
Object item = items.get(position);
if (item instanceof Event) {
return VIEW_TYPE_EVENT;
} else {
return VIEW_TYPE_DATE;
}
}
}


@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v;
ViewHolder vh;
if (viewType == VIEW_TYPE_EVENT) {
v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.item_event, parent, false);
vh = new ViewHolderEvent(v);
} else if (viewType == VIEW_TYPE_DATE) {
v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.item_event_date, parent, false);
vh = new ViewHolderDate(v);
} else {
v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.item_event_empty, parent, false);
vh = new ViewHolder(v);
}


return vh;
}


@Override
public void onBindViewHolder(EventAdapter.ViewHolder viewHolder,
final int position) {
int viewType = getItemViewType(position);
if (viewType == VIEW_TYPE_EVENT) {
//...
} else if (viewType == VIEW_TYPE_DATE) {
//...
} else if (viewType == VIEW_TYPE_EMPTY) {
//...
}
}


public static class ViewHolder extends ParentViewHolder {
public ViewHolder(View v) {
super(v);
}
}


public static class ViewHolderDate extends ViewHolder {
public ViewHolderDate(View v) {
super(v);
}
}


public static class ViewHolderEvent extends ViewHolder {
public ViewHolderEvent(View v) {
super(v);
}
}


}
小开

RVEmptyObserver

而不是使用自定义RecyclerView，扩展AdapterDataObserver是一个更简单的解决方案，允许设置一个自定义View，当列表中没有项时显示:

使用示例:

RVEmptyObserver observer = new RVEmptyObserver(recyclerView, emptyView)
rvAdapter.registerAdapterDataObserver(observer);

类:

public class RVEmptyObserver extends RecyclerView.AdapterDataObserver {
private View emptyView;
private RecyclerView recyclerView;


public RVEmptyObserver(RecyclerView rv, View ev) {
this.recyclerView = rv;
this.emptyView    = ev;
checkIfEmpty();
}


private void checkIfEmpty() {
if (emptyView != null && recyclerView.getAdapter() != null) {
boolean emptyViewVisible = recyclerView.getAdapter().getItemCount() == 0;
emptyView.setVisibility(emptyViewVisible ? View.VISIBLE : View.GONE);
recyclerView.setVisibility(emptyViewVisible ? View.GONE : View.VISIBLE);
}
}


public void onChanged() { checkIfEmpty(); }
public void onItemRangeInserted(int positionStart, int itemCount) { checkIfEmpty(); }
public void onItemRangeRemoved(int positionStart, int itemCount) { checkIfEmpty(); }
}
小开

下面是我的类，用于显示空视图、重试视图(当加载api失败时)和RecyclerView的加载进度

public class RecyclerViewEmptyRetryGroup extends RelativeLayout {
private RecyclerView mRecyclerView;
private LinearLayout mEmptyView;
private LinearLayout mRetryView;
private ProgressBar mProgressBar;
private OnRetryClick mOnRetryClick;


public RecyclerViewEmptyRetryGroup(Context context) {
this(context, null);
}


public RecyclerViewEmptyRetryGroup(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}


public RecyclerViewEmptyRetryGroup(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}


@Override
public void onViewAdded(View child) {
super.onViewAdded(child);
if (child.getId() == R.id.recyclerView) {
mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
return;
}
if (child.getId() == R.id.layout_empty) {
mEmptyView = (LinearLayout) findViewById(R.id.layout_empty);
return;
}
if (child.getId() == R.id.layout_retry) {
mRetryView = (LinearLayout) findViewById(R.id.layout_retry);
mRetryView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mRetryView.setVisibility(View.GONE);
mOnRetryClick.onRetry();
}
});
return;
}
if (child.getId() == R.id.progress_bar) {
mProgressBar = (ProgressBar) findViewById(R.id.progress_bar);
}
}


public void loading() {
mRetryView.setVisibility(View.GONE);
mEmptyView.setVisibility(View.GONE);
mProgressBar.setVisibility(View.VISIBLE);
}


public void empty() {
mEmptyView.setVisibility(View.VISIBLE);
mRetryView.setVisibility(View.GONE);
mProgressBar.setVisibility(View.GONE);
}


public void retry() {
mRetryView.setVisibility(View.VISIBLE);
mEmptyView.setVisibility(View.GONE);
mProgressBar.setVisibility(View.GONE);
}


public void success() {
mRetryView.setVisibility(View.GONE);
mEmptyView.setVisibility(View.GONE);
mProgressBar.setVisibility(View.GONE);
}


public RecyclerView getRecyclerView() {
return mRecyclerView;
}


public void setOnRetryClick(OnRetryClick onRetryClick) {
mOnRetryClick = onRetryClick;
}


public interface OnRetryClick {
void onRetry();
}
}

activity_xml

<...RecyclerViewEmptyRetryGroup
android:id="@+id/recyclerViewEmptyRetryGroup">


<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"/>


<LinearLayout
android:id="@+id/layout_empty">
...
</LinearLayout>


<LinearLayout
android:id="@+id/layout_retry">
...
</LinearLayout>


<ProgressBar
android:id="@+id/progress_bar"/>


</...RecyclerViewEmptyRetryGroup>

enter image description here

源在这里https://github.com/PhanVanLinh/AndroidRecyclerViewWithLoadingEmptyAndRetry

小开

如果你正在使用一个FirebaseRecyclerAdapter，这篇文章就像一个魅力https://stackoverflow.com/a/39058636/6507009

小开

因为Kevin的答案不完整 如果你使用RecyclerAdapter的notifyItemInserted和notifyItemRemoved来更新数据集，这是更正确的答案。 请参阅下面添加的另一个用户的Kotlin版本。< / p >

Java:

mAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {


@Override
public void onChanged() {
super.onChanged();
checkEmpty();
}


@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
checkEmpty();
}


@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
super.onItemRangeRemoved(positionStart, itemCount);
checkEmpty();
}


void checkEmpty() {
mEmptyView.setVisibility(mAdapter.getItemCount() == 0 ? View.VISIBLE : View.GONE);
}
});

芬兰湾的科特林

adapter.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
override fun onChanged() {
super.onChanged()
checkEmpty()
}


override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
super.onItemRangeInserted(positionStart, itemCount)
checkEmpty()
}


override fun onItemRangeRemoved(positionStart: Int, itemCount: Int) {
super.onItemRangeRemoved(positionStart, itemCount)
checkEmpty()
}


fun checkEmpty() {
empty_view.visibility = (if (adapter.itemCount == 0) View.VISIBLE else View.GONE)
}
})
小开

在自定义RecyclerView中使用AdapterDataObserver

芬兰湾的科特林:

RecyclerViewEnum.kt

enum class RecyclerViewEnum {
LOADING,
NORMAL,
EMPTY_STATE
}

RecyclerViewEmptyLoadingSupport.kt

class RecyclerViewEmptyLoadingSupport : RecyclerView {


var stateView: RecyclerViewEnum? = RecyclerViewEnum.LOADING
set(value) {
field = value
setState()
}
var emptyStateView: View? = null
var loadingStateView: View? = null




constructor(context: Context) : super(context) {}


constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {}


constructor(context: Context, attrs: AttributeSet, defStyle: Int) : super(context, attrs, defStyle) {}




private val dataObserver = object : AdapterDataObserver() {
override fun onChanged() {
onChangeState()
}


override fun onItemRangeRemoved(positionStart: Int, itemCount: Int) {
super.onItemRangeRemoved(positionStart, itemCount)
onChangeState()
}


override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
super.onItemRangeInserted(positionStart, itemCount)
onChangeState()
}
}




override fun setAdapter(adapter: RecyclerView.Adapter<*>?) {
super.setAdapter(adapter)
adapter?.registerAdapterDataObserver(dataObserver)
dataObserver.onChanged()
}




fun onChangeState() {
if (adapter?.itemCount == 0) {
emptyStateView?.visibility = View.VISIBLE
loadingStateView?.visibility = View.GONE
this@RecyclerViewEmptyLoadingSupport.visibility = View.GONE
} else {
emptyStateView?.visibility = View.GONE
loadingStateView?.visibility = View.GONE
this@RecyclerViewEmptyLoadingSupport.visibility = View.VISIBLE
}
}


private fun setState() {


when (this.stateView) {
RecyclerViewEnum.LOADING -> {
loadingStateView?.visibility = View.VISIBLE
this@RecyclerViewEmptyLoadingSupport.visibility = View.GONE
emptyStateView?.visibility = View.GONE
}


RecyclerViewEnum.NORMAL -> {
loadingStateView?.visibility = View.GONE
this@RecyclerViewEmptyLoadingSupport.visibility = View.VISIBLE
emptyStateView?.visibility = View.GONE
}
RecyclerViewEnum.EMPTY_STATE -> {
loadingStateView?.visibility = View.GONE
this@RecyclerViewEmptyLoadingSupport.visibility = View.GONE
emptyStateView?.visibility = View.VISIBLE
}
}
}
}

layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">


<LinearLayout
android:id="@+id/emptyView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white"
android:gravity="center"
android:orientation="vertical">


<TextView
android:id="@+id/emptyLabelTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="empty" />
</LinearLayout>


<LinearLayout
android:id="@+id/loadingView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white"
android:gravity="center"
android:orientation="vertical">


<ProgressBar
android:id="@+id/progressBar"
android:layout_width="45dp"
android:layout_height="45dp"
android:layout_gravity="center"
android:indeterminate="true"
android:theme="@style/progressBarBlue" />
</LinearLayout>


<com.peeyade.components.recyclerView.RecyclerViewEmptyLoadingSupport
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>

在活动中使用这种方式:

recyclerView?.apply {
layoutManager = GridLayoutManager(context, 2)
emptyStateView = emptyView
loadingStateView = loadingView
adapter = adapterGrid
}


// you can set LoadingView or emptyView manual
recyclerView.stateView = RecyclerViewEnum.EMPTY_STATE
recyclerView.stateView = RecyclerViewEnum.LOADING
小开

另一种方法是使用addOnChildAttachStateChangeListener来处理RecyclerView中出现/消失的子视图。

recyclerView.addOnChildAttachStateChangeListener(new RecyclerView.OnChildAttachStateChangeListener() {
@Override
public void onChildViewAttachedToWindow(@NonNull View view) {
forEmptyTextView.setVisibility(View.INVISIBLE);
}


@Override
public void onChildViewDetachedFromWindow(@NonNull View view) {
forEmptyTextView.setVisibility(View.VISIBLE);
}
});
小开

如果你想在回收器视图为空时显示一个文本视图，你可以这样做:

ArrayList<SomeDataModel> arrayList = new ArrayList<>();


RecycleAdapter recycleAdapter =  new RecycleAdapter(getContext(),project_Ideas);


recyclerView..setAdapter(recycleAdapter);


if(arrayList.isEmpty())
{
emptyTextView.setVisibility(View.VISIBLE);
recyclerView.setVisibility(View.GONE);
}

我假设你有TextView

和这样的XML

 android:visibility="gone"
小开

最简单的解决方案是使用RecyclerView。AdapterDataObserver，并在适配器初始化后将其注册到recyclerview中。

val emptyDataObserver = EmptyDataObserver(recycler_view, empty_data_parent)
yourAdapter.registerAdapterDataObserver(emptyDataObserver)

其中，recycler_view &empty_data_parent是你的活动中的布局，约束这些视图作为你想要的，并使其可见性走了。然后创建自己的空数据集视图image &文本。

 <include
android:id="@+id/empty_data_parent"
layout="@layout/item_empty_dataset"
android:layout_width="match_parent"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="parent"
android:layout_height="match_parent"
android:layout_gravity="center" />

下面是empty_data_set_view.xml的一个例子

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
android:layout_gravity="center"
android:gravity="center"
android:paddingTop="10dp"
android:paddingBottom="10dp"
tools:ignore="RtlHardcoded">


<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.422"
android:src="@drawable/ic_empty_dataset_1" />


<TextView
android:id="@+id/title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Title is called when title is placed"
android:padding="10dp"
android:fontFamily="@font/normal"
android:textStyle="bold"
android:gravity="center"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/imageView2" />


<TextView
android:id="@+id/sub_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text=" Subtitle is called when title is placed. Subtitle is called when title is placed"
android:padding="5dp"
android:fontFamily="@font/normal"
android:gravity="center"
android:layout_marginStart="10dp"
android:layout_marginEnd="10dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/title" />
</androidx.constraintlayout.widget.ConstraintLayout>

这个EmptyDataObserver类将做这项工作。

import android.view.View
import androidx.recyclerview.widget.RecyclerView




class EmptyDataObserver constructor(rv: RecyclerView?, ev: View?): RecyclerView.AdapterDataObserver() {


private var emptyView: View? = null
private var recyclerView: RecyclerView? = null


init {
recyclerView = rv
emptyView = ev
checkIfEmpty()
}




private fun checkIfEmpty() {
if (emptyView != null && recyclerView!!.adapter != null) {
val emptyViewVisible = recyclerView!!.adapter!!.itemCount == 0
emptyView!!.visibility = if (emptyViewVisible) View.VISIBLE else View.GONE
recyclerView!!.visibility = if (emptyViewVisible) View.GONE else View.VISIBLE
}
}


override fun onChanged() {
super.onChanged()
checkIfEmpty()
}


override fun onItemRangeChanged(positionStart: Int, itemCount: Int) {
super.onItemRangeChanged(positionStart, itemCount)
}


}
小开

这是如何显示空视图而使用LiveData过滤和更新RecyclerView

    ViewModel.getInstance().getCustomers?.observe(viewLifecycleOwner, {customerList ->
//assign your adapter with your list then
listAdapter?.notifyDataSetChanged()
isListItemEmpty(customerList?.isEmpty())
}

创建一个接口来在适配器和片段之间通信，并在适配器中注册它

 interface EmptyListener {
fun isListEmpty(isEmpty: Boolean)
}

然后在publishResults中调用它:

        dataList?.isEmpty()?.let { mListener?.isListEmpty(it) }

最后在Fragment中实现你的接口:

 override fun isListEmpty(isEmpty: Boolean) {
if (isEmpty) {
your_list?.visibility = View.GONE
empty_view?.visibility = View.VISIBLE
} else {
empty_view?.visibility = View.GONE
your_list?.visibility = View.VISIBLE
}
}

提交答案