经过程序代码向RadioGroup中添加RadioButton,结果文字不显示

通过程序代码向RadioGroup中添加RadioButton,结果文字不显示
for(int i = 0; i < addr_list.size();i ++){
MyAddrInfo addr = addr_list.get(i);
StringBuilder sb = new StringBuilder("");
sb.append(addr.getAdress()+"\n");
sb.append(addr.getName()+" "+addr.getPhone());
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.WRAP_CONTENT);
RadioButton rb = new RadioButton(this);
rb.setText(sb.toString());
rb.setButtonDrawable(R.drawable.radio_check_button_selector);

rb.setTextSize(R.dimen.titleSize);
rb.setTextColor(android.R.color.black);
rb.setLayoutParams(params);
address.addView(rb);
}
求高手指教！
------解决思路----------------------
rb.setTextSize(res.getDimen(R.dimen.titleSize));
------解决思路----------------------
为何是LayoutParams.MATCH_PARENT