How to create PopupWindow on startup in android?

Question

It is possible using Dialog class but I do not want it that way. Instead I want it to be done by using PopupWindow class which gets popped up on startup and display some message on the popup. I am helpless, just can not getting this after spending many days behind it. Hope I get it here. Please and Thanks. Also look at below snippet if you didn't get what I want..

 public class PopupActivity extends Activity implements OnClickListener {


LinearLayout ll = new LinearLayout(this);
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(ll);

}

  protected void onStart()
 {
super.onStart();
final PopupWindow pw;
Button button = new Button(this);
button.setText("Hello");
pw = new PopupWindow(button, 245, 284, true);
button.setOnClickListener(new OnClickListener() {  
    @Override  
    public void onClick(View view) {  
        pw.dismiss();            
    }  
});

pw.showAsDropDown(ll, 10, -50);
} 

Above code gives me FORCE CLOSE :/ Help guys..

Answer 1

this is how you may show a popup window.

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="fill_parent" 
    android:layout_width="fill_parent"
    android:orientation="vertical"
    android:id="@+id/layoutTemp">

</LinearLayout>

popup_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dip"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#FFFFFF">

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:text="Test Pop-Up" />

</LinearLayout>

main.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    new Handler().postDelayed(new Runnable() {
        public void run() {
            showPopup();
        }
    }, 100);
}


public void showPopup(){
    LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    PopupWindow pw = new PopupWindow(inflater.inflate(R.layout.popup_layout, null, false), 100, 100, true);
    pw.showAtLocation(findViewById(R.id.layoutTemp), Gravity.CENTER, 0, 0);
}

The idea is that your popup will be displayed once your activity is loaded, otherwise it will produce exception Unable to add window -- token null is not valid; is your activity running?. Unless you show popup on a button click, that is the reason I'm showing it after a delay of 100 milliseconds (which is almost unnoticeable).