kotlin

Kotlin 是一种在 Java 虚拟机上运行的静态类型编程语言，被称之为 Android 世界的Swift，由 JetBrains 设计开发并开源。
Kotlin 可以编译成Java字节码，也可以编译成 JavaScript，方便在没有 JVM 的设备上运行。
在Google I/O 2017中，Google 宣布 Kotlin 成为 Android 官方开发语言。

kotlin中使用接近于Java的方式(内置类型)来表示数字，但是又不完全相同，
比如没有隐式转换！Kotlin中数字相关的内置类型如下：
需要注意几点：
● 1.没有自动向上转型，比如Int转Long，需要自己调toXxx方法转
● 2.Long类型结尾必须为大写的L，不能为小写，比如1024L
● 3.字符Char不是Number，用单引号来声明，比如’c’，不能像Java一样直接拿来当数字使，
如果你想把Char的值给Int，需要调toInt()方法
● 4.Boolean的值为true或false
● 5.Kotlin不支持8进制，十六进制0x开头，二进制0b开头k
● 6.位运算符，Java中的与或运算符用：|和&，kotlin中使用or和and关键字来替代
其他运算符也有分别的关键字替代：shl(有符号左移)，shr(有符号右移)，ushr(无符号右移)

LiseView

布局

<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=".MainActivity">
    <com.example.a123.dayk1.view.XListView
        android:id="@+id/mylist"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></com.example.a123.dayk1.view.XListView>
</android.support.constraint.ConstraintLayout>

BaseAdapter

class MyBaseAdapter (var content:Context , var list:ArrayList<MyFood>): BaseAdapter() {

override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
    var viewHolder:ViewHolder?
    var view:View?
    if (convertView==null){
        viewHolder=ViewHolder()
        view = View.inflate(content,R.layout.name1,null)
        viewHolder.title=view.findViewById(R.id.t1)
        viewHolder.foods=view.findViewById(R.id.t2)
        viewHolder.imag=view.findViewById(R.id.iv1)
        view.tag = viewHolder
    }else{
        view = convertView
        viewHolder = view.tag as ViewHolder
    }

    val get = list.get(position)
    viewHolder.title?.text = get.title
    viewHolder.foods?.text = get.foods
    Glide.with(content).load(get.pic).apply(RequestOptions.circleCropTransform()).into(viewHolder.imag)
    return view!!

}
inner class ViewHolder{
    var title:TextView? = null
    var foods:TextView? = null
    var imag:ImageView? = null
}

override fun getItem(position: Int): Any {
    return list.get(position)
}

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

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

自定义类

class MyFood  {
    var title:String? =null
    var foods:String? =null
    var pic:String? = null
constructor(title: String?, foods: String?, pic: String?) {
    this.title = title
    this.foods = foods
    this.pic = pic
}

override fun toString(): String {
    return "MyFood(title=$title, foods=$foods, pic=$pic)"
}

}

Activity

//*实现接口XListView*


    class MainActivity : AppCompatActivity(),XListView.IXListViewListener{
override fun onRefresh() {
    list.clear()
    page=1
    Thread(Runnable {
        val readText = URL("http://www.qubaobei.com/ios/cf/dish_list.php?stage_id=1&limit=10&page=$page").readText()
        val jsonObject = JSONObject(readText)
        val jsonArray = jsonObject.getJSONArray("data")
        for (i in 0..jsonArray.length()-1 step 1){
            val jsonObject1 = jsonArray.getJSONObject(i)
            val title = jsonObject1.getString("title")
            val food_str = jsonObject1.getString("food_str")
            val pic = jsonObject1.getString("pic")
            list.add(MyFood(title,food_str,pic))
        }
    }).start()
    myBaseAdapter = MyBaseAdapter(this, list)
    mylist.adapter = myBaseAdapter
    myBaseAdapter!!.notifyDataSetChanged()
    load()
}

override fun onLoadMore() {

    page+=1
    Thread(Runnable {
        val readText = URL("http://www.qubaobei.com/ios/cf/dish_list.php?stage_id=1&limit=10&page=$page").readText()
        val jsonObject = JSONObject(readText)
        val jsonArray = jsonObject.getJSONArray("data")
        for (i in 0..jsonArray.length()-1 step 1){
            val jsonObject1 = jsonArray.getJSONObject(i)
            val title = jsonObject1.getString("title")
            val food_str = jsonObject1.getString("food_str")
            val pic = jsonObject1.getString("pic")
            list.add(MyFood(title,food_str,pic))
        }
    }).start()

    load()
}

 fun load(){
    mylist.stopLoadMore()
     mylist.stopRefresh()

}

var list:ArrayList<MyFood> = ArrayList()
var page:Int = 1
var myBaseAdapter:MyBaseAdapter? =null
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

        Thread(Runnable {
            val readText = URL("http://www.qubaobei.com/ios/cf/dish_list.php?stage_id=1&limit=20&page=$page").readText()
            val jsonObject = JSONObject(readText)
            val jsonArray = jsonObject.getJSONArray("data")
            for (i in 0..jsonArray.length()-1 step 1){
                val jsonObject1 = jsonArray.getJSONObject(i)
                val title = jsonObject1.getString("title")
                val food_str = jsonObject1.getString("food_str")
                val pic = jsonObject1.getString("pic")
                list.add(MyFood(title,food_str,pic))
            }
            myBaseAdapter!!.notifyDataSetChanged()
        }).start()



    myBaseAdapter = MyBaseAdapter(this, list)
    mylist.adapter = myBaseAdapter

    mylist.setPullLoadEnable(true)
    mylist.setPullRefreshEnable(true)
    mylist.setXListViewListener(this)

}
}