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?
•PrimeAdapter
通过使用PrimeAdapter，在RecyclerViews中处理分隔符可以非常简单。它为创建和管理分隔器提供了多种功能和更大的灵活性。
您可以按以下方式创建适配器(请参阅GitHub中关于使用的完整文档):
val adapter = PrimeAdapter.with(recyclerView)
.setLayoutManager(LinearLayoutManager(activity))
.set()
.build(ActorAdapter::class.java)
创建适配器实例后，您可以简单地使用以下命令添加分隔符:
//----- Default divider:
adapter.setDivider()
//----- Divider with a custom drawable:
adapter.setDivider(ContextCompat.getDrawable(context, R.drawable.divider))
//----- Divider with a custom color:
adapter.setDivider(Color.RED)
//----- Divider with a custom color and a custom inset:
adapter.setDivider(Color.RED, insetLeft = 16, insetRight = 16)
//----- Deactivate dividers:
adapter.setDivider(null)
如果你想为物品添加相同的空间，最简单的方法是为RecycleView添加顶部+左侧填充，为卡片物品添加右侧+底部空白。
文件dimens.xml
<resources>
<dimen name="divider">1dp</dimen>
</resources>
文件list_item.xml
<CardView
android:layout_marginBottom="@dimen/divider"
android:layout_marginRight="@dimen/divider">
...
</CardView>
文件list.xml
<RecyclerView
...
android:paddingLeft="@dimen/divider"
android:paddingTop="@dimen/divider" />
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>
我觉得需要一个简单的、不使用XML的、基于代码的答案
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(), DividerItemDecoration.VERTICAL);
ShapeDrawable shapeDrawableForDivider = new ShapeDrawable(new RectShape());
int dividerThickness = // (int) (SomeOtherView.getHeight() * desiredPercent);
shapeDrawableForDivider.setIntrinsicHeight(dividerThickness);
shapeDrawableForDivider.setAlpha(0);
dividerItemDecoration.setDrawable(shapeDrawableForDivider);
recyclerView.addItemDecoration(dividerItemDecoration);
我非常喜欢这个答案，我用Kotlin的单一表达式重新写了一遍:
recyclerView.addItemDecoration(DividerItemDecoration(this,DividerItemDecoration.VERTICAL).also { deco ->
with (ShapeDrawable(RectShape())){
intrinsicHeight = (resources.displayMetrics.density * 24).toInt()
alpha = 0
deco.setDrawable(this)
}
})
这和@Nerdy最初的答案是一样的，只是它将分隔线的高度设置为24dp，而不是另一个视图高度的百分比。
