以下のような感じで書いてるのですがRadioButtonをグループ化できません
どうしたらグループ化することができますか？

LinearLayout linearLayout = new LinearLayout(this);
linearLayout.setOrientation(LinearLayout.VERTICAL);
setContentView(linearLayout);

radioGroup = new RadioGroup(this);
LinearLayout.LayoutParams layoutParams = new RadioGroup.LayoutParams(
RadioGroup.LayoutParams.WRAP_CONTENT,
RadioGroup.LayoutParams.WRAP_CONTENT);
radioButton1 = new RadioButton(this);
radioButton1.setText("testes");
radioGroup.addView(radioButton1, layoutParams);
radioButton2 = new RadioButton(this);
radioButton2.setText("wwwwww");
radioGroup.addView(radioButton2, layoutParams);
linearLayout.addView(radioGroup, new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));