Question

我试图在ListView中显示一个数组，但是我的MainActivity的最后两行会抛出一条Expecting member declaration消息。知道为什么吗？

MainActivity.kt

package com.example.apple.stories

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.ListView
import org.jetbrains.anko.db.MapRowParser

class MainActivity : AppCompatActivity() {

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

    val authors = arrayOf("Conan Doyle, Arthur", "Christie, Agatha", "Collins, Wilkie");

    val listView = ListView(this);

    val adapter = ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, authors);

    listView.adapter = adapter;

    activity_main.addView(listView);

}

activity_main.xml中

<?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"
    tools:context="com.example.apple.stories.MainActivity">

    <ListView
        android:fillViewport="true"
        android:id="@+id/listView" />

</android.support.constraint.ConstraintLayout>

Answer 1

有一个例子here。

基本上，Java中的代码非常相似：

class ListExampleAdapter(context: Context) : BaseAdapter() {
        internal var sList = arrayOf("One", "Two", "Three", "Four", "Five", "Six", "Seven",
                "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen")
        private val mInflator: LayoutInflater

        init {
            this.mInflator = LayoutInflater.from(context)
        }

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

        override fun getItem(position: Int): Any {
            return sList[position]
        }

        override fun getItemId(position: Int): Long {
            return position.toLong()
        }

        override fun getView(position: Int, convertView: View?, parent: ViewGroup): View? {
            val view: View?
            val vh: ListRowHolder
            if (convertView == null) {
                view = this.mInflator.inflate(R.layout.list_row, parent, false)
                vh = ListRowHolder(view)
                view.tag = vh
            } else {
                view = convertView
                vh = view.tag as ListRowHolder
            }

            vh.label.text = sList[position]
            return view
        }
    }

    private class ListRowHolder(row: View?) {
        public val label: TextView

        init {
            this.label = row?.findViewById(R.id.label) as TextView
        }

}

然后，将适配器包含在ListView：

中

val lv = findViewById(R.id.list) as ListView
lv.adapter = ListExampleAdapter(this)

Answer 2

以下适配器将满足您的需求

class MyArrayAdapter(val contexts: Context, val array: ArrayList<String>)
: ArrayAdapter<String>(contexts, android.R.layout.simple_list_item_1, array) {
companion object {
    class Holder {
        var textView: TextView? = null
    }
}

override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
    var holder: Holder;
    if (convertView == null) {
        val view = LayoutInflater.from(context).inflate(android.R.layout.simple_list_item_1, parent, false)
        holder = Holder()
        holder.textView = view.findViewById(android.R.id.text1)
        holder.textView?.text = array[position]
        view.tag = holder
        return view;
    } else {
        holder = convertView.tag as Holder
        holder.textView?.text=array[position]
        return convertView
    }
}


}

然后设置适配器

val adapter = MyArrayAdapter<String>(this authors);

    listView.adapter = adapter;

在Kotlin中从数组填充ListView

2 个答案: