This an example from my code how to address a widget(button) in popupwindow
View v=LayoutInflater.from(getContext()).inflate(R.layout.popupwindow, null, false);
final PopupWindow pw = new PopupWindow(v,500,500, true);
final Button button = rootView.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
pw.showAtLocation(rootView.findViewById(R.id.constraintLayout), Gravity.CENTER, 0, 0);
}
});
final Button popup_btn=v.findViewById(R.id.popupbutton);
popup_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
popup_btn.setBackgroundColor(Color.RED);
}
});
Hope this help you