Android Code and JS interaction

The younger brother now needs Android code and JS interaction. There is a problem, ask everyone to take the belt.

My page:
<! DOCTYPE html>

<meta charset= "UTF-8" >
<meta name= "viewport" content= "Width=device-width,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no" >
<script>
function Fuck ()
{
var docel = document.www.yxin7.com documentelement
Alert (Fuck.sayhello ());
}
</script>
<title> title </title>

<body>
I'm a test file. <button onclick= () > Click Test </button>
</body>

My JS Injection interface:
Web.addjavascriptinterface (New www.xbyl688.com htmlinterface (), "fuck");

Injection class:
Class htmlinterface{
Public Htmlinterface () {
}
@JavascriptInterface
public void Logdevicesize (String width,string height)
{
LOG.I ("chocolater517", "width=" +width+ "; height=" +height);
}

@JavascriptInterface
Public String SayHello ()
{
Return "The Million grass mud horse flew over";
};
}

However, the Web page will report such errors:
[Info:console (31)] "Www.honqili66.com uncaught typeerror:object function fuck ()
{
var docel = document.documentelement
Alert (Fuck.sayhello ());
} has no method ' SayHello ', source:file:///android_asset/testpage/www.zgktv.cn welcome.html (31)

But I can write and execute it:
Web.loadurl ("Javascript:alewww.jyz521.com RT (Fuck.sayhello ())");

Android Code and JS interaction