1.效果图：

2.主界面：

package com.ufi.pdioms.ztkotlin

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.AdapterView
import android.widget.ArrayAdapter
import kotlinx.android.synthetic.main.activity_main.*
import java.util.ArrayList

class MainActivity : AppCompatActivity(),AdapterView.OnItemSelectedListener {
    override fun onNothingSelected(p0: AdapterView<*>?) {

    }

    override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
        Log.e("TAG","position: "+p2+",content: "+p0!!.getItemAtPosition(p2).toString())
    }

    val categories = ArrayList<String>()


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

        categories.add("shubham")
        categories.add("karan")
        categories.add("arjun")
        categories.add("arsh")

        val adapter = ArrayAdapter(this, R.layout.color_spinner_layout, categories)
        adapter.setDropDownViewResource(R.layout.spinner_dropdown_layout)
        spinner.adapter = adapter
        spinner.setOnItemSelectedListener(this)

    }
}

3.主界面布局：

  <Spinner
        android:id="@+id/spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        tools:ignore="MissingConstraints" />

4.简单布局1： 

color_spinner_layout

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:text="@string/app_name"
    android:padding="10dp"
    android:textSize="20sp"
    android:textColor="@android:color/holo_orange_dark"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

5.简单布局2：

spinner_dropdown_layout

<?xml version="1.0" encoding="utf-8"?>
<CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:text="@string/app_name"
    android:padding="10dp"
    android:textSize="20sp"
    android:textColor="@android:color/holo_green_dark"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

</CheckedTextView>

end，本demo从一个java例子，简单修改而来