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)

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>

这个链接对我来说很有吸引力:

https://gist.github.com/lapastillaroja/858caf1a82791b6c1a36

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.View;

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private Drawable mDivider;
    private boolean mShowFirstDivider = false;
    private boolean mShowLastDivider = false;


    public DividerItemDecoration(Context context, AttributeSet attrs) {
        final TypedArray a = context
                .obtainStyledAttributes(attrs, new int[]{android.R.attr.listDivider});
        mDivider = a.getDrawable(0);
        a.recycle();
    }

    public DividerItemDecoration(Context context, AttributeSet attrs, boolean showFirstDivider,
            boolean showLastDivider) {
        this(context, attrs);
        mShowFirstDivider = showFirstDivider;
        mShowLastDivider = showLastDivider;
    }

    public DividerItemDecoration(Drawable divider) {
        mDivider = divider;
    }

    public DividerItemDecoration(Drawable divider, boolean showFirstDivider,
            boolean showLastDivider) {
        this(divider);
        mShowFirstDivider = showFirstDivider;
        mShowLastDivider = showLastDivider;
    }

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

        if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
            outRect.top = mDivider.getIntrinsicHeight();
        } else {
            outRect.left = mDivider.getIntrinsicWidth();
        }
    }

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

        // Initialization needed to avoid compiler warning
        int left = 0, right = 0, top = 0, bottom = 0, size;
        int orientation = getOrientation(parent);
        int childCount = parent.getChildCount();

        if (orientation == LinearLayoutManager.VERTICAL) {
            size = mDivider.getIntrinsicHeight();
            left = parent.getPaddingLeft();
            right = parent.getWidth() - parent.getPaddingRight();
        } else { //horizontal
            size = mDivider.getIntrinsicWidth();
            top = parent.getPaddingTop();
            bottom = parent.getHeight() - parent.getPaddingBottom();
        }

        for (int i = mShowFirstDivider ? 0 : 1; i < childCount; i++) {
            View child = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

            if (orientation == LinearLayoutManager.VERTICAL) {
                top = child.getTop() - params.topMargin;
                bottom = top + size;
            } else { //horizontal
                left = child.getLeft() - params.leftMargin;
                right = left + size;
            }
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }

        // show last divider
        if (mShowLastDivider && childCount > 0) {
            View child = parent.getChildAt(childCount - 1);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            if (orientation == LinearLayoutManager.VERTICAL) {
                top = child.getBottom() + params.bottomMargin;
                bottom = top + size;
            } else { // horizontal
                left = child.getRight() + params.rightMargin;
                right = left + size;
            }
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

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

然后在你的活动中:

mCategoryRecyclerView.addItemDecoration(
    new DividerItemDecoration(this, null));

或者如果你使用片段:

mCategoryRecyclerView.addItemDecoration(
    new DividerItemDecoration(getActivity(), null));

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)

下面是我在Kotlin中如何做的，在项目之间设置一个默认大小为10dp的简单空间:

class SimpleItemDecoration(context: Context, space: Int = 10) : RecyclerView.ItemDecoration() {

    private val spaceInDp = ConvertUtil.dpToPx(context, space)

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {

        outRect.left = spaceInDp
        outRect.right = spaceInDp
        outRect.bottom = spaceInDp
        // Add top margin only for the first item to avoid double space between items
        if (parent.getChildAdapterPosition(view) == 0) {
            outRect.top = spaceInDp
        }
    }
}

这是dpToPx方法:

fun dpToPx(context: Context, dp: Int): Int {
        return (dp * context.resources.displayMetrics.density).toInt()
    }

然后像这样将它添加到RecyclerView中:(感谢@MSpeed)

recyclerView.addItemDecoration(SimpleItemDecoration(context))

•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)