如何在 RecyclerView 中的项目之间添加分隔符和空格

Question

这是以前在 ListView 类中使用 divider 和 dividerHeight 参数如何完成的示例：

 <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"/>

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"/>

在这种情况下，是否可以定义边距和/或将自定义分隔线视图直接添加到列表项的布局中，还是有更好的方法来实现我的目标？

原文由 EyesClear 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

将 RecyclerView 与 ItemDecorations 一起使用 - Kotlin android 中的基本分隔符示例

一个完整的示例，包括构建器、添加边距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。只需添加您的装饰以及您的 recyclerView 初始设置的其余部分。

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

原文由 Kumar Santanu 发布，翻译遵循 CC BY-SA 4.0 许可协议