android - RecyclerView 和 Intent：没有为参数“ListUserAdapter”传递值

Question

嗨，我目前在我的 android 项目中使用 kotlin，按照说明，我被告知要制作一个具有回收视图的应用程序，以在您单击显示的列表之一时显示列表项和意图。 但是当我想运行应用程序时出现此错误，错误是“没有为参数'ListUserAdapter'传递值”这是我的代码

列表用户适配器.kt

class ListUserAdapter(private val ListUserAdapter: ArrayList<User>) : RecyclerView.Adapter<ListUserAdapter.ListViewHolder>() {
private lateinit var onItemClickCallBack: OnItemClickCallBack

fun setOnItemClickCallback(onItemClickCallback: OnItemClickCallBack) {
    this.onItemClickCallBack = onItemClickCallback
}

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ListViewHolder {
    val view: View = LayoutInflater.from(parent.context).inflate(R.layout.row_user, parent, false)
    return ListViewHolder(view)
}

override fun onBindViewHolder(holder: ListViewHolder, position: Int) {
    val (name, username) = ListUserAdapter[position]
    holder.tvName.text = name
    holder.tvUserName.text= username
    holder.itemView.setOnClickListener {
        onItemClickCallBack.onItemClicked(ListUserAdapter[holder.adapterPosition])
    }
}

override fun getItemCount(): Int = ListUserAdapter.size


class ListViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    var tvName: TextView = itemView.findViewById(R.id.tv_username)
    var tvUserName: TextView = itemView.findViewById(R.id.tv_name)
}

interface OnItemClickCallBack {
    fun onItemClicked(data : User)
}

}

MainActivity.kt

class MainActivity : AppCompatActivity() {

private lateinit var adapter: ListUserAdapter
private lateinit var dataName: Array<String>
private lateinit var dataUsername: Array<String>
private lateinit var dataLocation: Array<String>
private lateinit var dataRepo: Array<String>
private lateinit var dataCompany: Array<String>
private lateinit var dataFollowers: Array<String>
private lateinit var dataFollowing: Array<String>
private lateinit var dataPhoto: TypedArray
private var users = arrayListOf<User>()
private lateinit var binding: ActivityMainBinding

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityMainBinding.inflate(layoutInflater)
    setAdapter()
    prepare()
    addItem()
}

private fun setAdapter() {
    adapter = ListUserAdapter() //error in here
    with(binding) {
        rvList.adapter = adapter
        rvList.layoutManager =
            GridLayoutManager(this@MainActivity, 2, GridLayoutManager.HORIZONTAL, false)
        rvList.setHasFixedSize(true)
    }
    adapter.setOnItemClickCallback(object : ListUserAdapter.OnItemClickCallBack{
        override fun onItemClicked(user: User) {
            val intent = Intent(this@MainActivity, DetailActivity::class.java)
            intent.putExtra(DetailActivity.KEY_USER, user)
            startActivity(intent)
        }

    })
}


private fun prepare() {
    dataName = resources.getStringArray(R.array.name)
    dataUsername = resources.getStringArray(R.array.username)
    dataPhoto = resources.obtainTypedArray(R.array.avatar)
    dataLocation = resources.getStringArray(R.array.location)
    dataRepo = resources.getStringArray(R.array.repository)
    dataCompany = resources.getStringArray(R.array.company)
    dataFollowers = resources.getStringArray(R.array.followers)
    dataFollowing = resources.getStringArray(R.array.following)
}

private fun addItem() {
    for (position in dataName.indices) {
        val user = User(
            dataUsername[position],
            dataName[position],
            dataLocation[position],
            dataCompany[position],
            dataRepo[position],
            dataFollowers[position],
            dataFollowing[position],
            dataPhoto.getResourceId(position, -1)
        )
        users.add(user)
    }
}

}

详细活动.kt

class DetailActivity : AppCompatActivity() {

private lateinit var binding: ActivityDetailBinding

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityDetailBinding.inflate(layoutInflater)
    setContentView(binding.root)
    setData()
}


private fun setData() {
    val dataUser = intent.getParcelableExtra<User>(KEY_USER) as User
    with(binding) {
        Glide.with(root)
            .load(dataUser.photo)
            .circleCrop()
            .into(ivDetailAvatar)
    }
}

companion object {
    const val KEY_USER = "key_user"
}

}

Answer 1

您只是忘记了构造函数参数:)

您的适配器 class 需要接收要实例化的User的ArrayList ，您已经在Activity中拥有它，您只需将其作为构造函数参数传递:)

我还将参数名称重命名为users或usersList而不是 `ListUserAdapter 但因为目前它具有误导性，因为此参数不是适配器，它是用户列表。

只需将有错误的行更改为

adapter = ListUserAdapter(users)

但我认为你最好先调用prepare()和addItem()然后实例化你的适配器。 或者您可以实例化您的适配器，但也可以创建一个addItems function，因为它是适配器的最佳实践。

fun addItems(users: List<User>) {
    this.ListUserAdapter.addAll(users)
    notifyDataSetChanged()
}

并在onCreate中设置所有内容后使用它，执行类似的操作

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityMainBinding.inflate(layoutInflater)
    setAdapter()
    prepare()
    addItem()
    adapter.addItems(users)
}

但是您也可以重新组织这些方法以提高可读性，但它会起作用:)

Answer 2

只是你需要用adapter = ListUserAdapter(users)替换adapter = ListUserAdapter() //error in here然后你的问题就解决了