Android - How to add radio buttons to a radiogroup in another Activity? (programatically)

Question

I'm very new to programming with Android, so I'm making a simple text RPG to practice developing for the platform. The player has access to a menu, which shows their items as a group of Radio Buttons. That way one can be selected to Equip/sell/etc. The game is handled in a completely different Activity. I want a random event that can happen in the Game activity to be able to add a new custom Radio button to the Inventory Activity page. On my Inventory Activity page, I've written a simple method:

    public void addRadioButtons(){

        RadioGroup items=(RadioGroup) findViewById(R.id.invItems);
        RadioButton newItem = new RadioButton(this);
        newItem.setText("New Rare Item");
        newItem.setId(idCounter);
        idCounter++;
        items.addView(newItem);
}

When the random drop event is calculated in the Game Event, it just does a object.addRadioButtons() method call. This force closes every time, no matter what I try. I've also tried pre-formatting the button before adding it, also to no avail. Am I missing something?

Answer 1

It seems, that the reason in idCounter value. In Android view id must be calculated according to certain rules. Look at this post for more detals.