Android popup window dismissal

Do as per following it works fine:

PopupWindow pw;
LayoutInflater inflater = (LayoutInflater)this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View layout = inflater.inflate(R.layout.weight_popup, (ViewGroup)findViewById(R.id.linlay_weight_popup));
pw = new PopupWindow(layout,LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT, true);
pw.setBackgroundDrawable(new BitmapDrawable());
pw.setOutsideTouchable(true);
pw.showAsDropDown(btnSelectWeight);

This is because the popup window does not respond to onTouch or onKey events unless it has a background that != null. Check out some code I wrote to help with this. In the basic case you can to call PopupWindow#setBackgroundDrawable(new BitmapDrawable()) to force it to act the way you expect. You won't need your own onKey listener. You might also need to call PopupWindow#setOutsideTouchable(true) if you want it to go away when the user clicks outside of the window boundaries.

Extended esoteric answer:

The reason the background cannot be null is because of what happens in PopupWindow#preparePopup. If it detects background != null it creates an instance of PopupViewContainer and calls setBackgroundDrawable on that and puts your content view in it. PopupViewContainer is basically a FrameLayout that listens for touch events and the KeyEvent.KEYCODE_BACK event to dismiss the window. If background == null, it doesn't do any of that and just uses your content view. You can, as an alternative to depending on PopupWindow to handle that, extend your root ViewGroup to behave the way you want.

For new projects it's better to use

popupWindow.setBackgroundDrawable(new ColorDrawable());

instead of

popupWindow.setBackgroundDrawable(new BitmapDrawable());

as BitmapDrawable is deprecated. Also, it's better than ShapeDrawable in this case. I noticed that when PopupWindow is a rectangle with rounded corners, ShapeDrawable fills corners with black.

A really simple solution is to write pw.setFocusable(true), but probably you don't want to do this because then the MapActivity won't handle touch events.

A better solution is to override the back key, e.g like this:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {

    // Override back button
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        if (pw.isShowing()) {
            pw.dismiss();
            return false;
        }
    }
    return super.onKeyDown(keyCode, event);
} 

Good luck!