回收器视图和意图：没有为参数"列表用户适配器"传递值

Question

嗨，我目前正在为我的android项目使用kotlin，根据说明，我被告知要制作一个具有recycleview的应用程序，当你点击显示的列表之一时，它会显示列表项和意图。但当我想运行应用程序时，我遇到了这个错误，错误是"没有为参数"ListUserAdapter"传递值这是我的代码

ListUserAdapter.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)
}

}

主要活动.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)
}
}

}

DetailActivity.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

只需将adapter = ListUserAdapter() //error in here替换为adapter = ListUserAdapter(users)，即可解决问题

Answer 2

您只是忘记了构造函数参数：(

您的适配器类需要接收一个User的ArrayList才能实例化，您的Activity中已经有了它，您只需要将它作为构造函数参数传递：(

我也会将参数名称重命名为类似users或usersList的名称，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，所以它是用户列表。

只需将有错误的行更改为

adapter = ListUserAdapter(users)

但我认为最好先调用prepare()和addItem()，然后实例化适配器。或者，您可以实例化适配器，但也可以创建addItems函数，因为这是适配器的最佳实践。

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

并在onCreate内设置好所有内容后使用它，比如

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

但是您可能也可以重新组织这些方法来提高可读性，但它会起作用：(