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

public class CommonItemSpaceDecoration extends RecyclerView.ItemDecoration {

    private int mSpace = 0;
    private boolean mVerticalOrientation = true;

    public CommonItemSpaceDecoration(int space) {
        this.mSpace = space;
    }

    public CommonItemSpaceDecoration(int space, boolean verticalOrientation) {
        this.mSpace = space;
        this.mVerticalOrientation = verticalOrientation;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        outRect.top = SizeUtils.dp2px(view.getContext(), mSpace);
        if (mVerticalOrientation) {
            if (parent.getChildAdapterPosition(view) == 0) {
                outRect.set(0, SizeUtils.dp2px(view.getContext(), mSpace), 0, SizeUtils.dp2px(view.getContext(), mSpace));
            } else {
                outRect.set(0, 0, 0, SizeUtils.dp2px(view.getContext(), mSpace));
            }
        } else {
            if (parent.getChildAdapterPosition(view) == 0) {
                outRect.set(SizeUtils.dp2px(view.getContext(), mSpace), 0, 0, 0);
            } else {
                outRect.set(SizeUtils.dp2px(view.getContext(), mSpace), 0, SizeUtils.dp2px(view.getContext(), mSpace), 0);
            }
        }
    }
}

这将增加每个项目的顶部和底部(或左右)的空间。然后你可以将它设置为你的recyclerView。

recyclerView.addItemDecoration(new CommonItemSpaceDecoration(16));

文件SizeUtils.java

public class SizeUtils {
    public static int dp2px(Context context, float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }
}

其他回答

2016年10月更新

在v25.0.0支持库中,终于有了基本水平和垂直分隔符的默认实现!

DividerItemDecoration

实现它自己的RecyclerView版本。ItemDecoration

public class SpacingItemDecoration extends RecyclerView.ItemDecoration {
    private int spacingPx;
    private boolean addStartSpacing;
    private boolean addEndSpacing;

    public SpacingItemDecoration(int spacingPx) {
        this(spacingPx, false, false);
    }

    public SpacingItemDecoration(int spacingPx, boolean addStartSpacing, boolean addEndSpacing) {
        this.spacingPx = spacingPx;
        this.addStartSpacing = addStartSpacing;
        this.addEndSpacing = addEndSpacing;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        if (spacingPx <= 0) {
            return;
        }

        if (addStartSpacing && parent.getChildLayoutPosition(view) < 1 || parent.getChildLayoutPosition(view) >= 1) {
            if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
                outRect.top = spacingPx;
            } else {
                outRect.left = spacingPx;
            }
        }

        if (addEndSpacing && parent.getChildAdapterPosition(view) == getTotalItemCount(parent) - 1) {
            if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
                outRect.bottom = spacingPx;
            } else {
                outRect.right = spacingPx;
            }
        }
    }

    private int getTotalItemCount(RecyclerView parent) {
        return parent.getAdapter().getItemCount();
    }

    private int getOrientation(RecyclerView parent) {
        if (parent.getLayoutManager() instanceof LinearLayoutManager) {
            return ((LinearLayoutManager) parent.getLayoutManager()).getOrientation();
        } else {
            throw new IllegalStateException("SpacingItemDecoration can only be used with a LinearLayoutManager.");
        }
    }
}

这很简单,你不需要这么复杂的代码:

DividerItemDecoration divider = new DividerItemDecoration(
    mRVMovieReview.getContext(), DividerItemDecoration.VERTICAL
);
divider.setDrawable(
    ContextCompat.getDrawable(getBaseContext(), R.drawable.line_divider)
);

mRVMovieReview.addItemDecoration(divider);

将它添加到你的drawable: line_divide .xml中

<?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="@android:color/black" />
</shape>

这是我在Kotlin中为列显示(网格)所做的

  class ItemDecorationColumns(private val space: Int) : ItemDecoration() {

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val position = parent.getChildLayoutPosition(view)
        val manager = parent.layoutManager as GridLayoutManager?
        val spanCount = manager?.spanCount ?: 0

        if (position < spanCount) {
            outRect.top = space
        }

        if (position % 2 != 0) {
            outRect.right = space
        }
        outRect.left = space
        outRect.bottom = space
    }
}

使用

rvAlbums.addItemDecoration(ItemDecorationColumns(resources.getDimensionPixelSize(R.dimen.space)))

我们可以使用附加到recyclerview的各种装饰器来装饰物品,例如:

简单地使用下面的…从答案中提取

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

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

    private Drawable mDivider;

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

    /**
     * Custom divider will be used
     */
    public DividerItemDecoration(Context context, int resId) {
        mDivider = 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 + mDivider.getIntrinsicHeight();

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

然后用上面的方法如下:

RecyclerView.ItemDecoration itemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST);
recyclerView.addItemDecoration(itemDecoration);

这将在列表中的每个项目之间显示分隔符,如下所示:

对于那些想要了解更多细节的人,可以看看这个指南Using the recyclerview_ CodePath Android Cliffnotes。

这里的一些答案建议使用边距,但问题是:

如果你同时添加了上边距和下边距,它们将在项目之间显示为添加的,而且它们将太大。如果只添加其中之一,则整个列表的顶部或底部都没有边距。如果你在上面加上一半的距离,在下面加上一半的距离,外层的边缘就太小了。

因此,唯一美观上正确的解决方案是系统知道在哪里正确应用的分隔符:项目之间,但不是项目的上面或下面。