如何在RecycerView中添加项之间的分隔符和空格

Question

<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"/>

<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/或直接在列表项的布局中添加自定义分隔视图，或者是否有更好的方法来实现我的目标？

Answer 1

2016年10月更新

Android支持库的25.0.0版本引入了DividerItemDemorition类：

DividerItemDemoritage是一个RecycerView.ItemDemorition，可用作LinearLayoutManager项之间的分隔符。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

有些答案要么使用的方法后来被弃用，要么没有给出完整的解决方案，所以我试图做一个简短的最新总结。

所有项目装饰都按添加顺序绘制，在项目视图之前（在ondraw()中）和项目之后（在onDrawOver(canvas、recycerview、recycerview.state)中）。

扩展item装饰，添加一个自定义构造函数，它将spaceheight作为参数，并重写getitemoffsets()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;
    }
}

如果不想在最后一项下面插入空间，请添加以下条件：

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

注意：您还可以修改outrect.top、outrect.left和outrect.right属性以获得所需的效果。

扩展ItemDemargine并重写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);
        }
    }
}

您可以调用使用默认Android divider属性的第一个构造函数，也可以调用使用自己的drawable的第二个构造函数，例如drawable/divider.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>

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;
}

还有卢卡斯·罗查的图书馆，它应该简化物品装饰过程。不过我没试过。

其特点包括：

• 库存物品装饰品的集合，包括:
• 项间距水平/垂直分隔符。
• 列表项