简单的方法是为RecyclerView设置背景色，为项目设置不同的背景色。这里有一个例子……

<android.support.v7.widget.RecyclerView
    android:background="#ECEFF1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:scrollbars="vertical"/>

和TextView项目(它可以是任何东西)与底线“x”dp或px。

<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginBottom="1dp"
    android:background="#FFFFFF"/>

输出……

只需添加

recyclerView.addItemDecoration(new DividerItemDecoration(getContext(),
                DividerItemDecoration.VERTICAL));

此外，您可能还需要添加依赖项 实现“com.android.support: recyclerview-v7:28.0.0”

为了自定义它，你可以添加一个自定义drawable:

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

你可以自由地使用任何自定义绘图，例如:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
       android:shape="rectangle">
    <solid android:color="@color/colorPrimary"/>
    <size android:height="0.5dp"/>
</shape>

从谷歌搜索，添加这个ItemDecoration到你的RecyclerView:

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 the 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 { // hHorizontal
                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.");
        }
    }
}

为了在RecylerView中实现项目之间的间隔，我们可以使用ItemDecorators:

addItemDecoration(object : RecyclerView.ItemDecoration() {

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State,
    ) {
        super.getItemOffsets(outRect, view, parent, state)
        if (parent.getChildAdapterPosition(view) > 0) {
            outRect.top = 8.dp // Change this value with anything you want. Remember that you need to convert integers to pixels if you are working with dps :)
        }
    }
})

对于我粘贴的代码，有几件事需要考虑:

You don't really need to call super.getItemOffsets but I chose to, because I want to extend the behavior defined by the base class. If the library got an update doing more logic behind the scenes, we would miss it. As an alternative to adding top spacing to the Rect, you could also add bottom spacing, but the logic related to getting the last item of the adapter is more complex, so this might be slightly better. I used an extension property to convert a simple integer to dps: 8.dp. Something like this might work:

val Int.dp: Int
    get() = (this * Resources.getSystem().displayMetrics.density + 0.5f).toInt()

// Extension function works too, but invoking it would become something like 8.dp()

使用RecyclerView itemdecoration -一个基本的分隔符样本在Kotlin android

一个完整的示例，包括一个构建器，添加边缘或使用资源颜色的可能性

    class SeparatorDecoration constructor(ctx: Context, @ColorRes dividerColor: Int, heightDp: Float) :
    RecyclerView.ItemDecoration() {

    private val mPaints = Paint()

    init {
        mPaints.color = dividerColor
        val thickness = TypedValue.applyDimension(
            TypedValue.COMPLEX_UNIT_DIP,
            heightDp,
            ctx.resources.displayMetrics
        )
        mPaints.strokeWidth = thickness
    }

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val params = view.layoutParams as RecyclerView.LayoutParams

        // and add a separator to any view but the last one
        val p = params.viewAdapterPosition

        // and add a separator to any view but the last one
        if (p < state.itemCount) outRect[0, 0, 0] =
            mPaints.strokeWidth.toInt() // left, top, right, bottom
        else outRect.setEmpty() // 0, 0, 0, 0
    }

    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {

        // we set the stroke width before, so as to correctly draw the line we have to offset by width / 2
        val offset = (mPaints.strokeWidth / 2).roundToInt()

        // this will iterate over every visible view
        for (i in 0 until parent.childCount) {
            // get the view
            val view: View = parent.getChildAt(i)
            val params = view.layoutParams as RecyclerView.LayoutParams

            // get the position
            val position = params.viewAdapterPosition

            // and finally draw the separator
            if (position < state.itemCount) {
                c.drawLine(
                    view.left.toFloat(),
                    (view.bottom + offset).toFloat(),
                    view.right.toFloat(), (view.bottom + offset).toFloat(), mPaints
                )
            }
        }
    }
  }

设置很简单。只需将您的装饰与其余的初始设置一起添加到您的recyclerView。

 val decoration = SeparatorDecoration(context, R.color.primaryColor, 1.5f)
 recyclerview.addItemDecoration(decoration)

如果有人想为spaceBetween, paddingLeft, paddingTop, paddingRight和paddingBottom设置不同的值。

class ItemPaddingDecoration(
    private val spaceBetween: Int,
    private val paddingLeft: Int = spaceBetween,
    private val paddingTop: Int = spaceBetween,
    private val paddingRight: Int = spaceBetween,
    private val paddingBottom: Int = spaceBetween
) : RecyclerView.ItemDecoration() {

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val position = parent.getChildAdapterPosition(view)
        val orientation = when (val layoutManager = parent.layoutManager) {
            is LinearLayoutManager -> {
                layoutManager.orientation
            }
            is GridLayoutManager -> {
                layoutManager.orientation
            }
            else -> {
                RecyclerView.HORIZONTAL
            }
        }
        if (orientation == RecyclerView.HORIZONTAL) {
            when {
                position == 0 -> {
                    outRect.set(paddingLeft, paddingTop, spaceBetween, paddingBottom)
                }
                position < parent.adapter!!.itemCount - 1 -> {
                    outRect.set(0, paddingTop, spaceBetween, paddingBottom)
                }
                else -> {
                    outRect.set(0, paddingTop, paddingRight, paddingBottom)
                }
            }
        } else {
            when {
                position == 0 -> {
                    outRect.set(paddingLeft, paddingTop, paddingRight, paddingBottom)
                }
                position < parent.adapter!!.itemCount - 1 -> {
                    outRect.set(paddingLeft, 0, paddingRight, spaceBetween)
                }
                else -> {
                    outRect.set(paddingLeft, 0, paddingRight, paddingBottom)
                }
            }
        }
    }
}