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
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);
}
});
其他回答
在定义了RecyclerView的相同布局上，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。 如果数据集为空，那么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);
}
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);
}
});
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));
这里是我的类显示空视图，重试视图(当加载api失败时)和加载进度的RecyclerView
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>
来源在这里https://github.com/PhanVanLinh/AndroidRecyclerViewWithLoadingEmptyAndRetry
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(); }
}
