Android Alert Dialog

Alertdialog.java

AlertDialog ad = new AlertDialog.Builder(this).create();
ad.setCancelable(false); // This blocks the 'BACK' button
ad.setMessage("Hello World");
ad.setButton("OK", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        dialog.dismiss();                    
    }
});
ad.show();


//AlertDialog with Button
AlertDialog deleteAlert = new AlertDialog.Builder(this).create();
deleteAlert.setTitle("Delete List");
deleteAlert.setMessage("Are you sure you want to delete this list?");
deleteAlert.setButton("Yes", new OnClickListener(){

@Override
public void onClick(DialogInterface dialog, int which) {               
//...
}
});
deleteAlert.setButton2("No", new OnClickListener(){

@Override
public void onClick(DialogInterface dialog, int which) {
//...
}
});
deleteAlert.show();

//AlertDialog with items
final String [] items=new String []{"Item 1","Item 2","Item 3","Item 4"};
     AlertDialog.Builder builder=new AlertDialog.Builder(this);
     builder.setTitle("Items alert");
     
     builder.setItems(items, new OnClickListener() {
   
   @Override
   public void onClick(DialogInterface dialog, int which) {
    // TODO Auto-generated method stub
    TextView txt=(TextView)findViewById(R.id.txt);
    txt.setText(items[which]);
   }
  });
     
     builder.show();

//src: http://android-pro.blogspot.com/2010/09/using-alerts-in-android.html