AutoCompleteTextView problem in Dialog?

Question

dear friends,

i am trying to put Autocomplete text view in dialog but getting error on adaptor i have created new class extended by dialog and written following code.

AutoCompleteTextView textViewCountry = (AutoCompleteTextView) findViewById(com.example.FindItNear.R.id.autocomplete_radius);    
        ArrayAdapter adapter = new ArrayAdapter<String>(this,com.example.FindItNear.R.layout.list_item, RADIUS);    --> error here no constructor found
         textViewCountry.setAdapter(adapter);


    static final String[] RADIUS = new String[] 

 {
    "1",
    "5",
    "10",
    "25",
    "100",
    "125",
    "200",
    "250",
    "500",
    "750",
    "1000",
    "1250",
    "1500"
    };

but when i run same code on activity it works fine but in dialog it wont. any help would be appriciated.