Kotlin RecyclerView中ItemView类型不匹配与类型转换异常求助

问题描述 #

• 找不到独立的ItemView类型，只能使用MenuView.ItemView，但Glide报错：Type mismatch: inferred type is MenuView.ItemView but ImageView was expected
• 将类型改为ImageView后，抛出ClassCastException：androidx.constraintlayout.widget.ConstraintLayout cannot be cast to android.widget.ImageView

相关代码 #

inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    var tvName: TextView = itemView.findViewById(R.id.tvName)
    var tvAge: TextView = itemView.findViewById(R.id.tvAge)
    var ivProfile: ItemView = itemView.findViewById(R.id.ivProfile)

    fun bind(contact: Contact) {
        tvName.text = contact.name
        tvAge.text = "Age: ${contact.age}"

        Glide.with(context).load(contact.imageUrl).into (ivProfile)
    }
}

错误日志 #

类型不匹配错误 #

Type mismatch: inferred type is MenuView.ItemView but ImageView was expected.

类型转换异常 #

java.lang.ClassCastException: androidx.constraintlayout.widget.ConstraintLayout cannot be cast to android.widget.ImageView
                                    at com.jakob.kotlinrecyclerview.ContactAdapter$ViewHolder.<init>(ContactAdapter.kt:35)
                                    at com.jakob.kotlinrecyclerview.ContactAdapter.onCreateViewHolder(ContactAdapter.kt:17)
                                    at com.jakob.kotlinrecyclerview.ContactAdapter.onCreateViewHolder(ContactAdapter.kt:13)

解决方案 #

1. 纠正控件类型声明 #

你混淆了RecyclerView列表项的根布局itemView和MenuView.ItemView类。ivProfile是列表项布局中的ImageView控件，直接声明为ImageView即可，不需要用MenuView.ItemView。

2. 修复类型转换异常 #

出现ClassCastException是因为findViewById(R.id.ivProfile)获取到的是ConstraintLayout而非ImageView，按以下步骤排查：

• 检查列表项的布局XML文件，确认R.id.ivProfile对应的控件确实是ImageView，而非它的父布局ConstraintLayout
• 若ID无误，执行Clean Project后再Rebuild Project清除布局缓存

修正后的代码 #

inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    var tvName: TextView = itemView.findViewById(R.id.tvName)
    var tvAge: TextView = itemView.findViewById(R.id.tvAge)
    var ivProfile: ImageView = itemView.findViewById(R.id.ivProfile)

    fun bind(contact: Contact) {
        tvName.text = contact.name
        tvAge.text = "Age: ${contact.age}"

        Glide.with(itemView.context).load(contact.imageUrl).into(ivProfile)
    }
}

内容的提问来源于stack exchange，提问作者FleetAdmiralJakob