how to add listener to autocompletetextview, android?

In kotlin, this would be:

autoCompleteTextView.setOnItemClickListener { _, _, position, _ -> 
    // You can get the label or item that the user clicked:
    val value = adapter.getItem(position) ?: ""
    Toast.makeText(this, value, Toast.LENGTH_LONG).show();
}

I also recommend you name your variables starting with a lowercase letter to not confuse them with types.

try this:

phoneName.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View arg1, int pos,
                long id) {
              Toast.makeText(check.this," selected", Toast.LENGTH_LONG).show();

        }
    });