Android : appear a dialog in android

I want to appear a dialog in Android application, if the detector does not detect any card number it will remain blocked until the detection of the card number, and when the detector does not detect any card displays a default number is: 22222 I implemented this code but it does not work

        if(card==true)
                {
                    if((card.getIdValue()) == 22222 )
                    {
                         System.out.println("default value: "+card.getIdValue());
                         alertDialog1.show();
                         if((card.getIdValue()) != 22222 )
                         {
                            System.out.println("card number detected: "+card.getIdValue());
                            alertDialog1.dismiss();
                         }
                    }
                }

if you have a solution, please help me.