How to create custom Popup Menu using Kotlin in AndroidStudio?

for people who hate xml:

    private fun showOverflowMenu(context: Context, anchor: View) {
        val menu = PopupMenu(context, anchor)

        menu.menu.apply {
            add("Rename").setOnMenuItemClickListener {
                // TODO rename
                true
            }
            add("change context").setOnMenuItemClickListener {
                // change stuff
                true
            }

            add("delete").setOnMenuItemClickListener {
                // TODO delete some stuff
                true
            }
        }

        menu.show()
    }

Finally, I did it, It may help someone

Step 1. First, create an activity_main.xml contains a button named my_button

Step 2. Then take header_menu.xml under res/menu:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/header1"
        android:title="H1" />
    <item
        android:id="@+id/header2"
        android:title="H2" />
    <item
        android:id="@+id/header3"
        android:title="H3" />

</menu>

Step 3. Finally, in MainActivity.kt use it like:

class MainActivity : AppCompatActivity() {

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

        my_button.setOnClickListener {
             showPopup(my_button)
          }
    }

    private fun showPopup(view: View) {
        val popup = PopupMenu(this, view)
        popup.inflate(R.menu.header_menu)

        popup.setOnMenuItemClickListener(PopupMenu.OnMenuItemClickListener { item: MenuItem? ->

            when (item!!.itemId) {
                R.id.header1 -> {
                    Toast.makeText(this@MainActivity, item.title, Toast.LENGTH_SHORT).show()
                }
                R.id.header2 -> {
                    Toast.makeText(this@MainActivity, item.title, Toast.LENGTH_SHORT).show()
                }
                R.id.header3 -> {
                    Toast.makeText(this@MainActivity, item.title, Toast.LENGTH_SHORT).show()
                }
            }

            true
        })

        popup.show()
    }

Following Kotlin's nice and clean principle: You can do this as well:

1)in your .xml file: (but "onClick" in xml can be used while doing java as well)

<Button 
  ........
  android:onClick="showPopUp"
  ....../>

2)in your .kt file: (using kotlin's lambda expression)

fun showPopUp(view: View) {
    val popupMenu = PopupMenu(this, view)
    val inflater = popupMenu.menuInflater
    inflater.inflate(R.menu.header_menu, popupMenu.menu)
    popupMenu.show()

    popupMenu.setOnMenuItemClickListener {
        when(it.itemId) {
            R.id.header1 -> {
                Toast.makeText(this@MainActivity, item.title, Toast.LENGTH_SHORT).show();
            }
            R.id.header2 -> {
                Toast.makeText(this@MainActivity, item.title, Toast.LENGTH_SHORT).show();
            }
            R.id.header3 -> {
                Toast.makeText(this@MainActivity, item.title, Toast.LENGTH_SHORT).show();
            }
            ...........
        }
        true
    }
}