Cannot resolve method 'add(int, com.example.sky.myapplication.Fragment2)  

这是错误提示，

case R.id.button2:{
      Fragment2 fragment2=new Fragment2();
       FragmentManager fragmentManager=getSupportFragmentManager();
       FragmentTransaction beginTransaction=fragmentManager.beginTransaction();
       beginTransaction.add(R.id.Lin22,fragment2);
break;
}

这是我的代码  beginTransaction.add(R.id.Lin22,fragment2); 括号内报错