最简单的ReclyclerView增加分割线

实现代码

import android.content.res.Resources
import android.graphics.Rect
import android.util.TypedValue
import android.view.View
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.RecyclerView.ItemDecoration

/**
 * @data on  上午10:50
 * @author Kevin
 * @describe RecyclerView 分割线
 * @param space item之间间距
 * @param orientation 排列方向 垂直(VERTICAL) 水平(HORIZONTAL), 默认为垂直
 * @param startSpace 起始间距(第一个item距离屏幕左侧间距)
 * @param endSpace 终止间距(最后一个item离屏幕后侧间距)
 **/

class DefItemDecoration constructor(val space: Int = 0, private val orientation: DefOrientation? = DefOrientation.VERTICAL, private val startSpace: Int = 0, private val endSpace: Int = 0) : ItemDecoration() {

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val position = parent.getChildAdapterPosition(view)
        val totalCount = parent.adapter?.itemCount
        val defSpace = dip2px(space.toFloat())
        val defStartSpace = dip2px(startSpace.toFloat())
        val defEndSpace = dip2px(endSpace.toFloat())
        if (totalCount == 1) {
            if (orientation == DefOrientation.VERTICAL) {
                outRect.top = defStartSpace
                outRect.bottom = defEndSpace
            } else {
                outRect.left = defStartSpace
                outRect.right = defEndSpace
            }
            return
        }
        if (orientation == DefOrientation.VERTICAL) {
            when (position) {
                0 -> { //第一个
                    outRect.top = defStartSpace
                }
                totalCount?.minus(1) -> { //最后一个
                    if (totalCount == 2) {
                        outRect.top = defSpace / 2
                    }
                    outRect.bottom = defEndSpace
                }
                else -> { //中间其它的
                    outRect.top = defSpace / 2
                    outRect.bottom = defSpace / 2
                }
            }
        } else {
            when (position) {
                0 -> { //第一个
                    outRect.left = defStartSpace
                }
                totalCount?.minus(1) -> { //最后一个
                    if (totalCount == 2) {
                        outRect.left = defSpace / 2
                    }
                    outRect.right = defEndSpace
                }
                else -> { //中间其它的
                    outRect.left = defSpace / 2
                    outRect.right = defSpace / 2
                }
            }
        }
    }


    fun dip2px(dipValue: Float): Int {
        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dipValue, Resources.getSystem().displayMetrics).toInt()
    }

    enum class DefOrientation {
        VERTICAL, HORIZONTAL
    }
}

调用方式

 collocationRecyclerView?.apply {
            this.addItemDecoration(DefItemDecoration(30, DefItemDecoration.DefOrientation.HORIZONTAL))
        }