error find symbol in R.id. when build android cordova app

Question

Good day,

I would like to set the allowFileAccess to true in WebView websetting.

I try to do something as follow:

WebView webView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = webView.getSettings();
webSettings.setAllowFileAccess(true);

When I try to build my app, I hit the error: cannot find symbol.

Its pointing to the R.id., may I know what mistake I did?

The full error is as follow:

I am fresh to frontend, and never try native code before.

Or is there any other place I can do for this other than Activity.java?