这是之前在ListView类中使用divider和dividerHeight参数实现的一个例子:
<ListView
android:id="@+id/activity_home_list_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:divider="@android:color/transparent"
android:dividerHeight="8dp"/>
然而，在RecyclerView类中我没有看到这样的可能性。
<android.support.v7.widget.RecyclerView
android:id="@+id/activity_home_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"/>
在这种情况下，是否可以定义边距和/或直接添加自定义分隔符视图到列表项的布局中，或者是否有更好的方法来实现我的目标?
对于那些只在RecyclerView中寻找项目之间的空间的人，请参阅我的方法，在所有项目之间获得相等的空间，除了在第一个和最后一个项目中，我给出了较大的填充。我只应用填充左/右在水平的LayoutManager和顶部/底部在垂直的LayoutManager。
public class PaddingItemDecoration extends RecyclerView.ItemDecoration {
private int mPaddingPx;
private int mPaddingEdgesPx;
public PaddingItemDecoration(Activity activity) {
final Resources resources = activity.getResources();
mPaddingPx = (int) resources.getDimension(R.dimen.paddingItemDecorationDefault);
mPaddingEdgesPx = (int) resources.getDimension(R.dimen.paddingItemDecorationEdge);
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
final int itemPosition = parent.getChildAdapterPosition(view);
if (itemPosition == RecyclerView.NO_POSITION) {
return;
}
int orientation = getOrientation(parent);
final int itemCount = state.getItemCount();
int left = 0;
int top = 0;
int right = 0;
int bottom = 0;
/** Horizontal */
if (orientation == LinearLayoutManager.HORIZONTAL) {
/** All positions */
left = mPaddingPx;
right = mPaddingPx;
/** First position */
if (itemPosition == 0) {
left += mPaddingEdgesPx;
}
/** Last position */
else if (itemCount > 0 && itemPosition == itemCount - 1) {
right += mPaddingEdgesPx;
}
}
/** Vertical */
else {
/** All positions */
top = mPaddingPx;
bottom = mPaddingPx;
/** First position */
if (itemPosition == 0) {
top += mPaddingEdgesPx;
}
/** Last position */
else if (itemCount > 0 && itemPosition == itemCount - 1) {
bottom += mPaddingEdgesPx;
}
}
if (!isReverseLayout(parent)) {
outRect.set(left, top, right, bottom);
} else {
outRect.set(right, bottom, left, top);
}
}
private boolean isReverseLayout(RecyclerView parent) {
if (parent.getLayoutManager() instanceof LinearLayoutManager) {
LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
return layoutManager.getReverseLayout();
} else {
throw new IllegalStateException("PaddingItemDecoration can only be used with a LinearLayoutManager.");
}
}
private int getOrientation(RecyclerView parent) {
if (parent.getLayoutManager() instanceof LinearLayoutManager) {
LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
return layoutManager.getOrientation();
} else {
throw new IllegalStateException("PaddingItemDecoration can only be used with a LinearLayoutManager.");
}
}
}
文件dimens.xml
<resources>
<dimen name="paddingItemDecorationDefault">10dp</dimen>
<dimen name="paddingItemDecorationEdge">20dp</dimen>
</resources>
为了在RecylerView中实现项目之间的间隔，我们可以使用ItemDecorators:
addItemDecoration(object : RecyclerView.ItemDecoration() {
override fun getItemOffsets(
outRect: Rect,
view: View,
parent: RecyclerView,
state: RecyclerView.State,
) {
super.getItemOffsets(outRect, view, parent, state)
if (parent.getChildAdapterPosition(view) > 0) {
outRect.top = 8.dp // Change this value with anything you want. Remember that you need to convert integers to pixels if you are working with dps :)
}
}
})
对于我粘贴的代码，有几件事需要考虑:
You don't really need to call super.getItemOffsets but I chose to, because I want to extend the behavior defined by the base class. If the library got an update doing more logic behind the scenes, we would miss it.
As an alternative to adding top spacing to the Rect, you could also add bottom spacing, but the logic related to getting the last item of the adapter is more complex, so this might be slightly better.
I used an extension property to convert a simple integer to dps: 8.dp. Something like this might work:
val Int.dp: Int
get() = (this * Resources.getSystem().displayMetrics.density + 0.5f).toInt()
// Extension function works too, but invoking it would become something like 8.dp()
请注意一下Alex Fu在GitHub上的这个文件:
链接
它是“直接从支持演示中提取”的diveritemdecoration .java示例文件。
在我的项目中导入这个文件后，我能够很好地获得分隔线，并将其作为项目装饰添加到回收器视图。
下面是我的onCreateView在我的片段中包含Recyclerview的样子:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_recycler_view, container, false);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
mRecyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL));
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(getActivity());
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
return rootView;
}
我确信可以做额外的造型，但这只是一个起点。：）
public class VerticalItemDecoration extends RecyclerView.ItemDecoration {
private boolean verticalOrientation = true;
private int space = 10;
public VerticalItemDecoration(int value, boolean verticalOrientation) {
this.space = value;
this.verticalOrientation = verticalOrientation;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
RecyclerView.State state) {
// Skip first item in the list
if (parent.getChildAdapterPosition(view) != 0) {
if (verticalOrientation) {
outRect.set(space, 0, 0, 0);
} else if (!verticalOrientation) {
outRect.set(0, space, 0, 0);
}
}
}
}
mCompletedShippingRecyclerView.addItemDecoration(new VerticalItemDecoration(20,false));
Here is a simple hack to add a divider
Just add a background to the layout of your recycler item as follows
<?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:background="@drawable/shape_border"
android:gravity="center"
android:orientation="horizontal"
android:padding="5dp">
<ImageView
android:id="@+id/imageViewContactLogo"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_marginRight="10dp"
android:src="@drawable/ic_user" />
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0.92"
android:gravity="center|start"
android:orientation="vertical">
<TextView
android:id="@+id/textViewContactName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:singleLine="true"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textViewStatusOrNumber"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:singleLine="true"
android:text=""
android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>
<TextView
android:id="@+id/textViewUnreadCount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:padding="5dp"
android:text=""
android:textAppearance="?android:attr/textAppearanceMedium"
android:textColor="@color/red"
android:textSize="22sp" />
<Button
android:id="@+id/buttonInvite"
android:layout_width="54dp"
android:layout_height="wrap_content"
android:background="@drawable/ic_add_friend" />
</LinearLayout>
在drawable文件夹中创建以下shape_border.xml文件:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<gradient
android:angle="270"
android:centerColor="@android:color/transparent"
android:centerX="0.01"
android:startColor="#000" />
</shape>
这是最终的结果-一个带分隔符的RecyclerView。
