Kotlin学习笔记——Spinner

android提供的spinner

class MainActivity : AppCompatActivity() {
    val strs = arrayOf("1", "2","3","4","5", "6", "7","8","9","10","11","12","13","14","15","16")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val sp = findViewById<View>(R.id.spinner) as Spinner
        val startAdapter = ArrayAdapter(this, R.layout.support_simple_spinner_dropdown_item, strs)
        startAdapter.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item)
        sp.prompt = "请选择"
        sp.adapter = startAdapter
        sp.setSelection(0)
        var listen = myItemClickListener()
        sp.onItemSelectedListener = listen
    }
    internal inner class myItemClickListener : AdapterView.OnItemSelectedListener {
        override fun onNothingSelected(parent: AdapterView<*>?) {

        }
        override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
            toast("你的选择是：${strs[position]}")
        }
    }
}

步骤

1. 一个ArrayAdapter，参数分别是this，R.layout.support_simple_spinner_dropdown_item，Array<String>（到时候的item）
2. 刚才的ArrayAdapter设置效率视窗资源，调用setDropDownViewResource函数，参数是R.layout.support_simple_spinner_dropdown_item
3. 把ArrayAdapter赋值给spinner的adapter成员
4. 设置默认选项，setSelection
5. 如果想让spinner为对话框形式的，在xml文件中设置android:spinnerMode="Dialog",spinner的prompt成员为设置对话框标题的接口
6. 新建一个内部类，监听下拉选择，继承AdapterView.OnItemSelectedListener，重载onNothingSelected和onItemSelected两个方法
7. 新建监听器对象，通过spinner的onItemSelectedListener设置为监听器

anko库提供的spinner——selector

val strs = Arrayof("1", "2", "3")
aTextView.text = "假装这是一个spinner，其实我是TextView"
aTextView.setOnClickListener {
    selector("请选择", strs) { i -> 
        toast("你的选择是：${strs[i]}")
    }
}