RadioGroup and the button is in layout part for Dialog.. try as below
Dialog adc = new Dialog(this);
adc.setContentView(R.layout.config_dialog);
RadioGroup rg1 = (RadioGroup) adc.findViewById(R.id.radioGroup1);//check here
Button btn = (Button) adc.findViewById(R.id.button1);//check here
rg1.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
}
});
adc.setTitle("Custom Dialog");
adc.show();