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?


当前回答

以下是我的偷懒方法,但它很有效: 将CardView包装在一个布局中,并在父布局上设置一个填充/边距来模拟分隔符,并强制将普通分隔符设置为null。

文件list_item.xml

<LinearLayout
    android:id="@+id/entry_item_layout_container"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:paddingBottom="<divider_size>" > // This is the divider
    <CardView
        android:layout_width="<width_size>"
        android:layout_height="<height_size>">
        ...
    </CardView>
</LinearLayout

文件list.xml

<RecyclerView
    android:divider="@null"
    android:layout_width="<width_size>"
    android:layout_height="<height_size>"
    ...
/>

其他回答

为视图添加边距。这对我很管用。

android:layout_marginTop="10dp"

如果你只是想在XML中添加相等的间距,只需在RecyclerView中设置padding,并在你膨胀到RecyclerView中的项目中设置等量的layoutMargin,并让背景颜色决定间距颜色。

2016年10月更新

Android支持库25.0.0版本引入了DividerItemDecoration类:

DividerItemDecoration是一个RecyclerView。ItemDecoration,可以用作LinearLayoutManager的项目之间的分隔符。它支持水平和垂直方向。

用法:

DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
    layoutManager.getOrientation());
recyclerView.addItemDecoration(dividerItemDecoration);

以前的回答

有些答案使用的方法已经过时,或者没有给出完整的解决方案,所以我试着做一个简短的、最新的总结。


与ListView不同,RecyclerView类没有任何与分隔符相关的参数。相反,你需要扩展ItemDecoration,一个RecyclerView的内部类:

ItemDecoration允许应用程序向适配器数据集中的特定项视图添加特殊的绘图和布局偏移。这可以用于在项目之间绘制分隔线,高光,视觉分组边界等。 所有itemdecoration都按照它们被添加的顺序绘制,在项目视图之前(在onDraw())和在项目之后(在onDrawOver(Canvas, RecyclerView, RecyclerView. state)。

垂直间距

扩展ItemDecoration,添加一个自定义构造函数,将空格高度作为参数,并覆盖getitemoffset()方法:

public class VerticalSpaceItemDecoration extends RecyclerView.ItemDecoration {

    private final int verticalSpaceHeight;

    public VerticalSpaceItemDecoration(int verticalSpaceHeight) {
        this.verticalSpaceHeight = verticalSpaceHeight;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
            RecyclerView.State state) {
        outRect.bottom = verticalSpaceHeight;
    }
}

如果你不想在最后一项下面插入空格,添加以下条件:

if (parent.getChildAdapterPosition(view) != parent.getAdapter().getItemCount() - 1) {
            outRect.bottom = verticalSpaceHeight;
}

注意:你也可以修改outRect。前,outRect。left和outRect。正确的属性为期望的效果。

分配器ItemDecoration

扩展ItemDecoration并覆盖onDraw()方法:

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};

    private Drawable divider;

    /**
     * Default divider will be used
     */
    public DividerItemDecoration(Context context) {
        final TypedArray styledAttributes = context.obtainStyledAttributes(ATTRS);
        divider = styledAttributes.getDrawable(0);
        styledAttributes.recycle();
    }

    /**
     * Custom divider will be used
     */
    public DividerItemDecoration(Context context, int resId) {
        divider = ContextCompat.getDrawable(context, resId);
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();

        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);

            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + divider.getIntrinsicHeight();

            divider.setBounds(left, top, right, bottom);
            divider.draw(c);
        }
    }
}

你可以调用第一个构造函数使用默认的Android divider属性,也可以调用第二个构造函数使用你自己的drawable,例如drawable/divide .xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
       android:shape="rectangle">
    <size android:height="1dp" />
    <solid android:color="#ff992900" />
</shape>

注意:如果你想在你的项目上绘制分隔线,请重写onDrawOver()方法。

使用

要使用你的新类,添加VerticalSpaceItemDecoration或DividerSpaceItemDecoration到RecyclerView,例如在你的片段的onCreateView()方法中:

private static final int VERTICAL_ITEM_SPACE = 48;
private RecyclerView recyclerView;
private LinearLayoutManager linearLayoutManager;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_feed, container, false);

    recyclerView = (RecyclerView) rootView.findViewById(R.id.fragment_home_recycler_view);
    linearLayoutManager = new LinearLayoutManager(getActivity());
    recyclerView.setLayoutManager(linearLayoutManager);

    //add ItemDecoration
    recyclerView.addItemDecoration(new VerticalSpaceItemDecoration(VERTICAL_ITEM_SPACE));
    //or
    recyclerView.addItemDecoration(new DividerItemDecoration(getActivity()));
    //or
    recyclerView.addItemDecoration(
            new DividerItemDecoration(getActivity(), R.drawable.divider));

    recyclerView.setAdapter(...);

    return rootView;
}

还有Lucas Rocha的图书馆,旨在简化道具装饰过程。不过我还没试过。

其特点包括:

收藏的库存项目装饰,包括: 项目间距水平/垂直分隔。 列表项

而不是创建一个形状xml来改变分隔线的高度和颜色,你可以通过编程来创建它:

val divider = DividerItemDecoration(
                  context,
                  DividerItemDecoration.VERTICAL)

divider.setDrawable(ShapeDrawable().apply {
    intrinsicHeight = resources.getDimensionPixelOffset(R.dimen.dp_15)
    paint.color = Color.RED // Note:
                            //   Currently (support version 28.0.0), we
                            //   can not use tranparent color here. If
                            //   we use transparent, we still see a
                            //   small divider line. So if we want
                            //   to display transparent space, we
                            //   can set color = background color
                            //   or we can create a custom ItemDecoration
                            //   instead of DividerItemDecoration.
})

recycler_devices.addItemDecoration(divider)

我从一个旧的要点中分叉了DividerItemDecoration,并简化了它以适应我的用例,我还修改了它,以在ListView中绘制的方式绘制分隔符,包括在最后一个列表项之后的分隔符。这也会处理垂直的ItemAnimator动画:

1)将这个类添加到你的项目中:

public class DividerItemDecoration extends RecyclerView.ItemDecoration {
    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
    private Drawable divider;

    public DividerItemDecoration(Context context) {
        try {
            final TypedArray a = context.obtainStyledAttributes(ATTRS);
            divider = a.getDrawable(0);
            a.recycle();
        } catch (Resources.NotFoundException e) {
            // TODO Log or handle as necessary.
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        if (divider == null) return;
        if (parent.getChildAdapterPosition(view) < 1) return;

        if (getOrientation(parent) == LinearLayoutManager.VERTICAL)
            outRect.top = divider.getIntrinsicHeight();
        else
            throw new IllegalArgumentException("Only usable with vertical lists");
    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (divider == null) {
            super.onDrawOver(c, parent, state);
            return;
        }

        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();
        final int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; ++i) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int size = divider.getIntrinsicHeight();
            final int top = (int) (child.getTop() - params.topMargin - size + child.getTranslationY());
            final int bottom = top + size;
            divider.setBounds(left, top, right, bottom);
            divider.draw(c);

            if (i == childCount - 1) {
                final int newTop = (int) (child.getBottom() + params.bottomMargin + child.getTranslationY());
                final int newBottom = newTop + size;
                divider.setBounds(left, newTop, right, newBottom);
                divider.draw(c);
            }
        }
    }

    private int getOrientation(RecyclerView parent) {
        if (!(parent.getLayoutManager() instanceof LinearLayoutManager))
            throw new IllegalStateException("Layout manager must be an instance of LinearLayoutManager");
        return ((LinearLayoutManager) parent.getLayoutManager()).getOrientation();
    }
}

2)添加装饰器到你的RecylerView:

recyclerView.addItemDecoration(new DividerItemDecoration(getActivity()));
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));