Kotiln:将数据从适配器传递到活动

问题描述：

我尝试使用putExtra将数据从adapter传递到其他activity，但是当我单击列表中的项目以移动到第二个activity时，没有数据被检索，并且我输入的默认文本不会显示. 另一种方法呢?或我想念什么? 这是我的代码:

I try to pass my data from the adapter to my other activity with a putExtra but when I click on an item in my list to move to my second activity, no data is retrieved and the default text I put in is not displayed. another way to do? or What do I miss about it? Here my code :

我的onBindViewHolder:

override fun onBindViewHolder(holder: AlbumsListViewHolder, position: Int) {
    val AlbumsData = albumsData!![position]
    holder.albumsName.text = AlbumsData.title

    Glide.with(holder.itemView)
        .load(AlbumsData.cover)
        .transition(DrawableTransitionOptions.withCrossFade())
        .into(holder.coverImage)

    holder.itemView.setOnClickListener {
        val intent = Intent(holder.itemView.context, TracksActivity::class.java)
        //listener?.onClick(AlbumsData)
        intent.putExtra("dd", "ff")
        holder.itemView.context.startActivity(intent)
    }
}

我的第二个Activity:

class TracksActivity: AppCompatActivity(), TracksView {

    private var albumsAdapter: AlbumsAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)
        setContentView(R.layout.activity_tracks)

        //albumsAdapter = findViewById(R.id.trackslist_recycleview)
        val msg = intent.getStringExtra("dd")
        Log.d("dd", "${msg}")
    }
}

答

方法1:

您可以使用callback 首先，在适配器中定义一个回调，如下所示:

You can use callback First of all, define a callback in your adapter like this :

    interface CallbackInterface {   
        fun passDataCallback(message: String)
    }

然后在adapter中初始化回调interface:

class YourAdapter(private val callbackInterface:CallbackInterface) :
    RecyclerView.Adapter<CurrencyListAdapter.ViewHolder>() {
.
.
.
}

然后从onBindViewHolder()内部的接口使用回调方法，如下所示:

Then use the callback method from the interface inside your onBindViewHolder() like this :

holder.itemView.setOnClickListener {
        //Set your codes about intent here
        callbackInterface.passResultCallback("Your message")
}

最后，像这样在activity中实现callback方法:

And finally, implement your callback method in your activity like this :

class TracksActivity: AppCompatActivity(), TracksView , YourAdapterName.CallbackInterface {

    private var albumsAdapter: AlbumsAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)
        setContentView(R.layout.activity_tracks)
    }

  override fun passResultCallback(message: String) {
         //message is "ff"
    }
}

更新:

方法2:

如果您不使用callback，则只需将activity更改为:

If you dont use callback, as you wrote just change your activity to this :

class TracksActivity: AppCompatActivity(), TracksView {

    private var albumsAdapter: AlbumsAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)
        setContentView(R.layout.activity_tracks)

        var bundle : Bundle? = intent.extras
        var message = bundle!!.getString("dd") 
        Log.d("dd", "${message}")
    }
}

更新:2019年12月26日

方法3:KOTLIN BASE

我们可以将乐趣传递给适配器，并像这样从适配器获取数据:

We can pass a fun to adapter and get data from it like this :

在我们的适配器中:

class YourAdapter(private val clickListener: (yourData: YourData) -> Unit) :
    RecyclerView.Adapter<YourAdapter.ViewHolder>() {

//YourData like String

//And we have onCreateViewHolder like this 

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder = ViewHolder(
        LayoutInflater.from(parent.context).inflate(R.layout.your_item, parent,false),
        clickListener
    )

//And we have ViewHolder class like this 

  inner class ViewHolder(itemView: View, private val clickListener: (yourData: YourData) -> Unit) :
        RecyclerView.ViewHolder(itemView) {
.
.
.
     init {
            initClickListeners()
        }

//And pass data here with invoke


        private fun initClickListeners() {
            itemView.setOnClickListener { clickListener.invoke(yourData) }
        }
}

在我们的片段或活动中，我们可以通过以下方式获取数据:

In our fragment or activity we can get data with this way :

YourAdapter { yourData ->
            // we can use yourData here
            }

Kotiln:将数据从适配器传递到活动

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