ListView不可點擊（自定義適配器）

Question

我正在嘗試用羅馬創建一個簡單的RSS閱讀器。

我的准系統實現使用ListView和我的自定義Adapter用feed_stub.xml填充它。 單擊ListView項將啟動另一個活動。

到目前為止，我有兩個問題：

1. 我的ListView項目無法點擊 - 我的setOnItemClickListener未被觸發。

2. 如果我多次點擊某些項目，我的應用程序會因超出異常而崩潰。 這意味着我的適配器可能有錯誤。

來自activity_main.xml ListView

<ListView
            android:layout_width="0dp"
            android:layout_height="0dp" android:layout_marginTop="8dp"
            app:layout_constraintTop_toTopOf="parent" app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp"
            android:layout_marginBottom="8dp" app:layout_constraintBottom_toBottomOf="parent"
            android:id="@+id/rssListView" app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
            android:clickable="true" app:layout_constraintHorizontal_bias="0.0"
            app:layout_constraintVertical_bias="0.0"/>

我的MainActivity

import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Toast
import cz.cvut.lenguduy.rss.Downloader
import cz.cvut.lenguduy.view.ViewHolder
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    private val TAG = "MainActivity"

    private val downloader by lazy { Downloader(this, rssListView) }

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

        rssListView.setOnItemClickListener { parent, _, position, _ ->
            Log.d(TAG, "rssListView: item @pos $position clicked")
            val intent = Intent(this, SecondActivity::class.java)
            val item = parent.getItemAtPosition(position) as ViewHolder

            Toast.makeText(this, "clicked", Toast.LENGTH_LONG).show()

            intent.putExtra("title", item.tvName.text)
            intent.putExtra("text", item.tvSummary.text)
            this.startActivity(intent)
        }

        downloader.execute("http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/ws/RSS/topfreeapplications/limit=25/xml")
    }

    override fun onDestroy() {
        super.onDestroy()
        downloader.cancel(true)
    }
}

ViewHolder很簡單：

class ViewHolder(view: View) {
    val tvName: TextView = view.findViewById(R.id.tvName)
    val tvSummary: TextView = view.findViewById(R.id.tvSummary)
}

我的ListView使用feed_stub.xml ：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
                                             xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
                                             android:layout_height="match_parent">

    <TextView
            android:text="TextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/tvName" android:layout_marginTop="8dp"
            app:layout_constraintTop_toTopOf="parent" app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="16dp" app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="16dp" android:textSize="20sp" android:textStyle="bold" android:maxLines="2"
            android:clickable="true"/>
    <TextView
            android:text="TextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/tvSummary"
            app:layout_constraintTop_toBottomOf="@+id/tvName" app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="16dp" app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="16dp" android:maxLines="3" android:clickable="true"/>
</android.support.constraint.ConstraintLayout>

最后我的FeedAdapter ：

class FeedAdapter(context: Context,
                  private val resource: Int, private val feed: MutableList<Any?>)
    : ArrayAdapter<Article>(context, resource) {

    private val inflater = LayoutInflater.from(context)

    override fun getCount(): Int {
        return feed.size
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        val view: View
        val viewHolder: ViewHolder
        if(convertView == null) {
            view = inflater.inflate(resource, parent, false)
            viewHolder = ViewHolder(view)
            view.tag = viewHolder
        } else {
            view = convertView
            viewHolder = view.tag as ViewHolder
        }

        val currentEntry = feed[position] as SyndEntry

        viewHolder.tvName.text = currentEntry.title
        viewHolder.tvSummary.text = currentEntry.description.value

        return view
    }

    override fun isEnabled(position: Int): Boolean {
        return true
    }
}

大多數操作都是由我的偽控制器執行的：

class Downloader(context: Context, listView: ListView): AsyncTask<String, Void, String>() {
    private val TAG = "Downloader"

    private var propContext: Context by Delegates.notNull()
    private var propListView: ListView by Delegates.notNull()

    init {
        propContext = context
        propListView = listView
    }

    private lateinit var list: MutableList<Any?>

    override fun doInBackground(vararg url: String?): String {
        val input = SyndFeedInput()
        val feed = input.build(XmlReader(URL(url[0])))

        list = feed.entries

        return feed.toString()
    }

    override fun onPostExecute(result: String?) {
        super.onPostExecute(result)

        val feedAdapter = FeedAdapter(propContext, R.layout.feed_stub, list)
        propListView.adapter = feedAdapter
    }
}

那么為什么我的ListView項目不可點擊？

為什么我的應用程序在使用java.lang.IndexOutOfBoundsException: Invalid index 10, size is 0多次單擊后崩潰java.lang.IndexOutOfBoundsException: Invalid index 10, size is 0 ？

編輯：在FeedAdapter的getView()我添加了這個onClickListener：

convertView?.setOnClickListener() { v ->
            Log.d(TAG, "getView(): item clicked")

            val intent = Intent(context, SecondActivity::class.java)
            intent.putExtra("title", currentEntry.title)
            intent.putExtra("summary", currentEntry.description.value)

            context.startActivity(intent)
        }

現在我可以點擊它有時候。 我完全不知道為什么會這樣，但如果我隨機點擊，我將獲得去另一個活動的預期行為。

Answer 1

這是因為您尚未為viewHolder類實現onClickListener。 你已經實現了listView onItemClick Listener，它不適用於自定義適配器。 對於自定義適配器，您需要在getView方法中實現onClickListener。

override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        val view: View
        val viewHolder: ViewHolder
        if(convertView == null) {
            view = inflater.inflate(resource, parent, false)
            viewHolder = ViewHolder(view)
            view.tag = viewHolder
        } else {
            view = convertView
            viewHolder = view.tag as ViewHolder
        }

        val currentEntry = feed[position] as SyndEntry

        viewHolder.tvName.text = currentEntry.title
        viewHolder.tvSummary.text = currentEntry.description.value

        // set onClickListener for your ConvertView...
        convertView.setOnClickListener(context);    

        return view
    }

// now implement your on Click 
@Overriden
void onClick(View view){

}