Finestra popup

Rivedendo un appunto passato, a proposito delle finestre popup.
Ecco il codice, ricostruito da me ora:

package com.example.laboratorio21022016;

import android.app.Activity;
import android.graphics.Color;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
import android.widget.PopupWindow;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class MainActivity extends Activity {

 PopupWindow popupWindow;
 LinearLayout linearLayout;
 TextView textView;
 RelativeLayout mainLayout;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
  popupWindow=new PopupWindow(this);
  linearLayout=new LinearLayout(this);
  textView=new TextView(this);
  textView.setText("CIAO CICCIO");
  mainLayout=(RelativeLayout)findViewById(R.id.mainLayout);
  
  linearLayout.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
  linearLayout.setBackgroundColor(Color.YELLOW);
  linearLayout.addView(textView);
  popupWindow.setContentView(linearLayout);
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.main, menu);
  return true;
 }

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
  // Handle action bar item clicks here. The action bar will
  // automatically handle clicks on the Home/Up button, so long
  // as you specify a parent activity in AndroidManifest.xml.
  int id = item.getItemId();
  if (id == R.id.action_settings) {
   popupWindow.showAtLocation(mainLayout, 1, 100, 100);
   popupWindow.update(100,100);
   return true;
  }
  if(id==R.id.secondo_menu){
   popupWindow.dismiss();
  }
  return super.onOptionsItemSelected(item);
 }
}

...in modo da avere vita più facile di quanto l'ho avuta stasera non ricordando il codice per ottenerla!