如何用RecyclerView显示一个空视图?

我习惯于在布局文件中放置一个特殊的视图，如ListActivity文档中所述，在没有数据时显示。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" />

我想知道这如何能与新的RecyclerView?

当前回答

在自定义RecyclerView中使用AdapterDataObserver

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

2018-10-09 08:42:09

其他回答

RVEmptyObserver

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

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(); }
}

2017-05-13 13:18:25

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onCreateViewHolder上检查viewType是否为之前返回的视图，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;

2015-01-29 14:48:29

这是如何显示空视图，同时过滤和更新RecyclerView使用LiveData

    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
        }
    }

2021-09-03 17:34:30

在自定义RecyclerView中使用AdapterDataObserver

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

2018-10-09 08:42:09

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"
    />

and

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

2015-05-23 17:22:41

如何用RecyclerView显示一个空视图?

推荐文章

最新文章

标签