如何访问 RecyclerView 位置

Question

这里是初学者。好像我在这里遗漏了一些非常基本的东西，所以任何关于它是什么的资源或一个好的解释将不胜感激。

我用 PagerSnapHelper 添加了一个 Recycler View。我左右滑动，一切正常。现在，在我 activity_main.xml 的 TextView 中，我希望该应用程序显示适配器的当前位置。

执行此操作的最佳方法是什么？

我尝试了几件事，例如。 val pozycja adaptera = recyclerView.layoutManager.findContainingItemView() 或 getAdapterPosition() 的一些奇怪实例但我认为它们要么不适合这个场合，要么我只是用错了。

看看下面的代码：

class MainActivity : AppCompatActivity() {

@RequiresApi(Build.VERSION_CODES.O)

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    //Adding RecyclerView
    val recyclerView = findViewById<RecyclerView>(R.id.recyclerview_id)

    recyclerView.run {
        layoutManager = LinearLayoutManager(
            this@MainActivity,
            LinearLayoutManager.HORIZONTAL,
            false)
        adapter = MyAdapter()
        // This makes mood_layout snap to grid (full screen)
        PagerSnapHelper().attachToRecyclerView(this)
    }

    //Accessing Recycler View position

    val widokPozycji = findViewById<TextView>(R.id.textView_position)
    val pozycjaAdaptera = recyclerView.layoutManager.findContainingItemView()




    //Adding AlertDialog to add comments
    btn_addNote.setOnClickListener {
        //Setting Inflater to inflate Dialog with comment_edit_text.xml layout
        val dialogLayout = LayoutInflater.from(this).inflate(R.layout.comment_edit_text, null)
        val builder = AlertDialog.Builder(this)
            .setView(dialogLayout)
            .show()

        //Adding Shared Preferences to save a comment on confirmCommentButton button

        builder.confirmCommentButton.setOnClickListener {

            //creating instance of Shared Preferences
            val pref = getSharedPreferences("commentSharedPreferences", Context.MODE_PRIVATE)
            val editor = pref.edit()

            //ACCESSING COMMENT WRITTEN BY USER in AlertDialog.Builder - val builder
            val insertedName = builder.editTextComment.text.toString()

            //Saving shared Preferences
            editor.apply {
                putString("STRING_KEY", insertedName)
                apply()
            }

            // Toast to confirm saved data
            Toast.makeText(this, "Comment Saved", Toast.LENGTH_SHORT).show()
            //close Dialog on CONFIRM button click
            builder.dismiss()
        }
        //CANCEL button that closes Dialog on click
        builder.cancelCommentButton.setOnClickListener{
            builder.dismiss()
        }
        builder.setOnDismissListener {

        }
    }
}

//HISTORY button taking user to HistoryActivity on click

fun history(view: View) {
    // New Activity to open HistoryActivity
    var historyActivity: Intent = Intent(applicationContext, HistoryActivity::class.java)
    startActivity(historyActivity)
}
}

适配器：

class MyViewHolder(val view : View):RecyclerView.ViewHolder(view)

class MyAdapter : RecyclerView.Adapter<MyViewHolder>(){


override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {

    val layoutInflater = LayoutInflater.from(parent.context)
    val moodInflater = layoutInflater.inflate(R.layout.mood_layout, parent, false)
    return MyViewHolder(moodInflater)
}

override fun onBindViewHolder(holder: MyViewHolder, position: Int) {

    val context = holder.view.context

    val emoji = holder.view.emoji_img
    val background = holder.view.moodLayout_id
    val moodSelected = position

    when(moodSelected){
        0 -> {emoji.setImageResource(R.drawable.smiley_super_happy)
            background.setBackgroundColor(context.resources.getColor(R.color.banana_yellow))

        }

        1 -> {emoji.setImageResource(R.drawable.smiley_happy)
            background.setBackgroundColor(context.resources.getColor(R.color.light_sage))
        }

        2 -> {emoji.setImageResource(R.drawable.smiley_normal)
            background.setBackgroundColor(context.resources.getColor(R.color.cornflower_blue_65))
        }

        3 -> {emoji.setImageResource(R.drawable.smiley_disappointed)
            background.setBackgroundColor(context.resources.getColor(R.color.warm_grey))
        }

        4 -> {emoji.setImageResource(R.drawable.smiley_sad)
            background.setBackgroundColor(context.resources.getColor(R.color.faded_red))
        }
    }
}

override fun getItemCount(): Int {
    return 5
}
}

Answer 1

好的，所以我使用共享首选项来存储位置并能够从其他活动访问它。我把它们放在 onBindViewHolder 中。代码如下所示：

override fun onBindViewHolder(holder: MyViewHolder, position: Int) {

    val context = holder.view.context
    val sharedPref = holder.view.context.getSharedPreferences("position", MODE_PRIVATE)
    val editor = sharedPref.edit()

    editor.putInt("POSITION_KEY", position)
    editor.apply()

如何访问 RecyclerView 位置

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