通过代码动态创建UI时RecyclerView条目无法显示的问题

因需求原因，我希望完全通过代码而非XML动态创建UI，但当前遇到RecyclerView条目无法显示的问题——无论提供多少数据条目，都无法在屏幕上呈现。我已使用ConstraintLayout添加视图并设置固定高度，且借助AndroidView在Jetpack Compose中集成该RecyclerView，暂认为此集成方式并非问题诱因。

问题根源 #

1. ChatCell实现错误：

   • ChatCell继承自View（非ViewGroup），无法容纳子View，但构造函数中创建的ConstraintLayout未被关联到自身，导致item内部无实际内容。
   • 未给ChatCell设置有效布局参数，RecyclerView无法正确测量item宽高，最终导致条目不可见。

2. 冗余视图层级干扰：

   • createRecyclerView中创建的parent是普通View，属于多余层级，且错误地将RecyclerView约束到该View上，干扰了RecyclerView的正常布局逻辑。

修复后的代码 #

1. 修正ChatCell实现

将ChatCell改为继承ConstraintLayout，使其能正确容纳子View并设置布局：

class ChatCell(context: Context) : ConstraintLayout(context) {
    private val textView: TextView

    init {
        println("Created")
        id = View.generateViewId()

        textView = TextView(context).apply {
            id = View.generateViewId()
            text = "test"
            setBackgroundColor(context.getColor(R.color.red))
            layoutParams = LayoutParams(MATCH_PARENT, 100)
        }

        addView(textView)

        val constraintSet = ConstraintSet()
        constraintSet.clone(this)
        constraintSet.constrainHeight(textView.id, 100)
        constraintSet.connect(textView.id, ConstraintSet.LEFT, this.id, ConstraintSet.LEFT)
        constraintSet.connect(textView.id, ConstraintSet.TOP, this.id, ConstraintSet.TOP)
        constraintSet.connect(textView.id, ConstraintSet.RIGHT, this.id, ConstraintSet.RIGHT)
        constraintSet.applyTo(this)

        setBackgroundColor(context.getColor(R.color.red))
    }

    fun x() {}
}

2. 简化RecyclerView创建逻辑

移除冗余的parent View，直接将RecyclerView绑定到根ConstraintLayout：

fun createRecyclerView(context: Context): ConstraintLayout {
    val constraintLayout = createConstraintLayout(context)

    val recyclerView = RecyclerView(context).apply {
        id = View.generateViewId()
        layoutParams = ConstraintLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT)
        setBackgroundColor(context.getColor(R.color.purple_500))

        val shapeDrawable = MaterialShapeDrawable()
        shapeDrawable.fillColor = ColorStateList.valueOf(context.getColor(R.color.teal_200))
        shapeDrawable.setStroke(5f, context.getColor(R.color.red))
        background = shapeDrawable

        adapter = ChatAdapter()
        layoutManager = LinearLayoutManager(context, RecyclerView.VERTICAL, false)
    }

    constraintLayout.addView(recyclerView)

    val constraintSet = ConstraintSet()
    constraintSet.clone(constraintLayout)
    constraintSet.connect(recyclerView.id, ConstraintSet.LEFT, constraintLayout.id, ConstraintSet.LEFT)
    constraintSet.connect(recyclerView.id, ConstraintSet.TOP, constraintLayout.id, ConstraintSet.TOP)
    constraintSet.connect(recyclerView.id, ConstraintSet.RIGHT, constraintLayout.id, ConstraintSet.RIGHT)
    constraintSet.connect(recyclerView.id, ConstraintSet.BOTTOM, constraintLayout.id, ConstraintSet.BOTTOM)
    constraintSet.applyTo(constraintLayout)

    return constraintLayout
}

fun createConstraintLayout(context: Context): ConstraintLayout {
    return ConstraintLayout(context).apply {
        id = View.generateViewId()
        layoutParams = ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT)
    }
}

3. 其他辅助函数调整（可选）

保留简化视图创建的工具函数：

fun <T: View> applyDefaults(parent: ViewGroup, view: T, width: Int, height: Int): T {
    view.id = View.generateViewId()
    view.layoutParams = ConstraintLayout.LayoutParams(width, height)
    parent.addView(view)
    return view
}

内容的提问来源于stack exchange，提问作者J. Doe