Setting up radio button click ActionListeners
What GUI framework is this? Is the View v being passed to the OnClick method actually the clicked RadioButton? If so, here are some changes to consider

final RadioButton[] buttons = {radio_books,radio_games,radio_dvds,radio_electronics};

final OnClickListener onClickHandler =
    new OnClickListener() {
        @Override
        public void onClick(final View v) {
            final RadioButton checkedButton = (RadioButton) v;
            for (final RadioButton button : buttons) {
                if (button != checkedButton) {
                    button.setChecked(false);
                }
            }
        }
    };

for (final RadioButton button : buttons) {
    button.setOnClickListener(onClickHandler);
}


If View v != the checked radio button, then:

final RadioButton[] buttons = {radio_books,radio_games,radio_dvds,radio_electronics};
for (final RadioButton thisButton: buttons) {
    thisButton.setOnClickListener(
        new OnClickListener() {
            @Override
            public void onClick(final View v) {
                for (final RadioButton button : buttons) {
                    if (button != thisButton) {
                        button.setChecked(false);
                    }
                }
            }
        }
    );
}