Loadurl in a webview inside a @JavascriptInterface

Because I can not load WebView into html CADCLI using the code below. It does not recognize the Webview MainWeb that was created in MainActivity What settings do I need to make in the code to work?

@JavascriptInterface
public void action(String acao,String dados)  {
    if(acao.equals("AlterarCliente")){
        PrincipalWeb.loadUrl("v_cadcli");   
    }
}