android - 如何在RecyclerView中的项目之间添加分隔线和空格？(How to add dividers and spaces between items in RecyclerView?)

Question

This is an example of how it could have been done previously in the ListView class, using the divider and dividerHeight parameters:

(这是一个示例的示例，该示例可以使用divider和dividerHeight参数在先前的ListView类中完成：)

<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"/>

However, I don't see such possibility in the RecyclerView class.

(但是，我在RecyclerView类中看不到这种可能性。)

<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"/>

In that case, is it ok to define margins and/or add a custom divider view directly into a list item's layout or is there a better way to achieve my goal?

(在那种情况下，可以定义边距和/或将自定义分隔符视图直接添加到列表项的布局中，还是有更好的方法实现我的目标？)

  ask by EyesClear translate from so

Answer 1

October 2016 Update

(2016年10月更新)

The version 25.0.0 of Android Support Library introduced DividerItemDecoration class:

(Android支持库的DividerItemDecoration版本引入了DividerItemDecoration类：)

DividerItemDecoration is a RecyclerView.ItemDecoration that can be used as a divider between items of a LinearLayoutManager .

(DividerItemDecoration是RecyclerView.ItemDecoration，可以用作LinearLayoutManager项目之间的分隔线。)

It supports both HORIZONTAL and VERTICAL orientations.

(它同时支持HORIZONTAL和VERTICAL方向。)

Usage:

(用法：)

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

---

Previous answer

(先前的答案)

Some answers either use methods that have since become deprecated, or don't give a complete solution, so I tried to do a short, up-to-date wrap-up.

(有些答案要么使用自那以后就已弃用的方法，要么不提供完整的解决方案，因此我尝试进行简短的最新总结。)

---

Unlike ListView , the RecyclerView class has no divider-related parameters.

(与ListView不同， RecyclerView类没有与分隔符相关的参数。)

Instead, you need to extend ItemDecoration , a RecyclerView 's inner class:

(相反，您需要扩展ItemDecoration ，这是RecyclerView的内部类：)

An ItemDecoration allows the application to add a special drawing and layout offset to specific item views from the adapter's data set.

(ItemDecoration允许应用程序从适配器的数据集向特定的项目视图添加特殊的图形和布局偏移。)

This can be useful for drawing dividers between items, highlights, visual grouping boundaries and more.

(这对于在项目，突出显示，可视分组边界等之间绘制分隔线很有用。)

All ItemDecorations are drawn in the order they were added, before the item views (in onDraw() ) and after the items (in onDrawOver( Canvas , RecyclerView , RecyclerView.State) .

(在项目视图之前（在onDraw() ）和项目之后（在onDrawOver（ Canvas ， RecyclerView和RecyclerView.State) ，将按添加顺序绘制所有ItemDecorations 。)

Vertical spacing ItemDecoration (Vertical间距ItemDecoration)

Extend ItemDecoration , add custom constructor which takes space height as a parameter and override getItemOffsets() method:

(扩展ItemDecoration ，添加将空格height作为参数的自定义构造函数，并覆盖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;
    }
}

If you don't want to insert space below the last item, add the following condition:

(如果不想在最后一项下方插入空格，请添加以下条件：)

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

Note: you can also modify outRect.top , outRect.left and outRect.right properties for desired effect.

(注意：您也可以修改outRect.top ， outRect.left和outRect.right属性以获得所需的效果。)

Divider ItemDecoration (分频器项ItemDecoration)

Extend ItemDecoration and override onDraw() method:

(扩展ItemDecoration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);
        }
    }
}

You can either call the first constructor that uses the default Android divider attributes, or the second one that uses your own drawable, for example drawable/divider.xml

(您可以调用第一个使用默认Android除法器属性的构造函数，也可以调用第二个使用您自己的drawable的构造函数，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>

Note: if you want the divider to be drawn over your items, override onDrawOver() method instead.

(注意：如果要在项目上绘制分隔线，请onDrawOver()方法。)

Usage (用法)

To use your new class add VerticalSpaceItemDecoration or DividerSpaceItemDecoration to RecyclerView , for example in your fragment's onCreateView() method:

(要使用您的新类，例如，在片段的onCreateView()方法中，将VerticalSpaceItemDecoration或DividerSpaceItemDecoration添加到RecyclerView ：)

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;
}

---

There's also Lucas Rocha's library which is supposed to simplify the item decoration process.

(还有Lucas Rocha的图书馆 ，应该可以简化物品装饰过程。)

Haven't tried it though.

(还没有尝试过。)

Among its features are:

(其功能包括：)

• A collection of stock item decorations including:

  (库存物品装饰的集合，包括：)

• Item spacing Horizontal/vertical dividers.

  (项目间距水平/垂直分隔线。)

• List item

  (项目清单)