我得到的错误" LinearLayout不能被解析为类型"也有" Mulitple marker "

I'm new to Android and I'm trying out the Pinch to Zoom code. I get an error "LinearLayout cannot be resolved to a type" at this line. mainView =(LinearLayout)findViewById(R.id.linearLayout); Here is the code below can you help me resolve this issue. Thank you for your help.I'm new to Android and I'm trying out the Pinch