Kotlin 第一个 app

使用 RecycleView 显示测试数据显示结果

在activity_main.xml 添加对应控件布局（TextView RecycleView）

<?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.administrator.kotlintapplication.MainActivity">
    <TextView
        android:id="@+id/content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        android:text="test"/>
    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler"
        app:layout_constraintTop_toBottomOf="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</android.support.constraint.ConstraintLayout>

item_text.xml (TextView)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center_horizontal">
    <TextView
        android:id="@+id/item_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="25sp"/>
</LinearLayout>

MainActivity 相关代码

setContentView(R.layout.activity_main)
content.text = "Hello_Kotlin"
val list : MutableList<Test> = ArrayList()//创建一个可添加内容的List
for (i in 1..30){//添加数据
    list.add(Test("ff_" + i, "ff_hh_" + i))
}
recycler.layoutManager = LinearLayoutManager(this)//设置RecycleView 的 LayoutManager
val adapter = Adapter(this, list, { p, t ->
    Toast.makeText(this@MainActivity, "position= " + p +
            "\nname = " + t.n, Toast.LENGTH_SHORT).show()
})
recycler.adapter = adapter

Adapter 相关代码

class Adapter(context: Context, list: List<Test>, val itemListener: (Int, Test) -> Unit) : RecyclerView.Adapter<Adapter.ViewHolder>() {
    private var context: Context? = context
    private var list: List<Test>? = list
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val convertView = LayoutInflater.from(context).inflate(R.layout.item_text, parent, false)
        return ViewHolder(convertView)
    }
    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val t = list!![position]
        holder.textView.text = t.n
        holder.textView.setOnClickListener { itemListener(position, t) }
    }
    override fun getItemCount(): Int {
        return list!!.size
    }

    class ViewHolder(v: View) : RecyclerView.ViewHolder(v) {
        var textView: TextView = v.findViewById(R.id.item_content)
    }
}

OnItemClickListener 接口

interface OnItemClickListener {
    fun onItemClick(position: Int, test: Test)
}

Kotlin 创建类时会自动生成对应的 get/set方法

如果只有一个构造函数数时书写方法如下：

Test 类

class Test (name: String, surName: String){
    val n = name
    val sur = surName;
}

附带githup 链接地址 demo githup 地址

https://github.com/androidkf93/Kotlin.git

https://github.com/androidkf93/Kotlin.git

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