Recyclerview的Kotlin新片段

Question

I'm trying to open a new fragment from the current fragment's RecyclerView Adapter.But i don't know how to set onClickListener.. Here is my code

internal class ContentAdapter constructor (private var dataList: ArrayList<DataList>) : RecyclerView.Adapter<ContentAdapter.ViewHolder>(), View.OnClickListener {
    override fun onClick(v: View?) {
        val manager = activity.supportFragmentManager // I cannot resolve activity here 
        val transaction = manager.beginTransaction()
        val book = IndividualBook()
        transaction.add(android.R.id.content, book, "IndividualBook")
        transaction.addToBackStack(null)
        transaction.commit()
    }

    override fun getItemCount(): Int = dataList.size

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
        return ViewHolder(LayoutInflater.from(parent!!.context).inflate(R.layout.item,parent,false))
    }

    override fun onBindViewHolder(holder: ViewHolder?, position: Int) {
        holder!!.bind(dataList)
        holder.itemView.setOnClickListener(this)
    }

    class ViewHolder(itemView: View?) : RecyclerView.ViewHolder(itemView) {
        fun bind(DataList: ArrayList<DataList>){
            val dataList = DataList[adapterPosition]
            itemView.itemTitle.text = dataList.title
            Glide.with(itemView.context).load(dataList.image).into(itemView.itemImage)
            itemView.regPrice.text = dataList.regPrice
            itemView.regPrice.paintFlags = Paint.STRIKE_THRU_TEXT_FLAG
            itemView.splPrice.text = dataList.splPrice
        }
    }
}

Help me to solve the issue.

Answer 1

It will be better to use callback to activity to navigate to new fragment.

Change constructor to

internal class ContentAdapter constructor (private var dataList: ArrayList<DataList>,private var callback:()->Unit) : RecyclerView.Adapter<ContentAdapter.ViewHolder>(), View.OnClickListener 

Then inside

override fun onClick(v: View?)

put

callback.invoke();

Activity will set adapter by

val adapter = ContentAdapter(datalist)
{ // Code to navigate to new fragment

}

Answer 2

internal class ContentAdapter (private val activity: Activity, private var dataList: ArrayList<DataList>) : RecyclerView.Adapter<ContentAdapter.ViewHolder>(), View.OnClickListener

You need to pass the activity in your constructor. And a nice bonus tip for kotlin: If you have only one primary constructor you don't have to write the "constructor" prefix

Answer 3

internal class ContentAdapter (private val activity: AppCompatActivity, private var dataList: ArrayList<DataList>) : RecyclerView.Adapter<ContentAdapter.ViewHolder>(), View.OnClickListener

When you have the activity you can access the manager

You need to pass the activity in the constructor And a kotlin tip if you have only one primary constructor you don't have to write it.

Answer 4

A few solutions:

1. Kotlin defaults all classes to static . You have to opt-in to them being inner classes. Put the class inside of an Activity, and add the inner modifier to the class:

    internal inner class ContentAdapter constructor (private var dataList: ArrayList<DataList>) : RecyclerView.Adapter<ContentAdapter.ViewHolder>(), View.OnClickListener { 

2. Keep the ContentAdapter static , but pass the activity in through the constructor:

    internal class ContentAdapter( private val activity: AppCompatActivity, private var dataList: ArrayList<DataList> ) : RecyclerView.Adapter<ContentAdapter.ViewHolder>(), View.OnClickListener { 

It looks like you probably aren't familiar with the ways that Kotlin differs from Java and defaults you to writing better code. It might help for you to read through the Kotlin documentation in entirety. It's not very long. I also recommend Kotlin Koans which are coding exercises JetBrains provides to practice Kotlin.

Kotlin is a huge improvement over Java :-) Don't let this discourage you!

(By the way, it looks like you can probably make your dataList a val . val is always preferred over var when the reference is final .)

Answer 5

Use Onclick as alternative of onClickListener, you can use onClick like this.

 itemView.regPrice.onClick {
/ * your action */
}