在ContactListActivity中，点击未选中的item将其选中，再点击已选中的item撤销其选中

public void onItemClick(AdapterView<?> parent, View view, int position,

        long id) {

    ContactListAdapter.ViewHolder viewHolder = null;

    if(mListAdapter.bShowCheckBox) {

        viewHolder = (ContactListAdapter.ViewHolder)view.getTag();

        TxrjContact contact = (TxrjContact)mListAdapter.getItem(position);

        contact.setSelected(!contact.isSelected());

        viewHolder.select

                .setImageBitmap(contact.isSelected() ? mListAdapter.checkBox

                        : mListAdapter.unCheckBox);

    }

}