Javascript를 통해 Activity의 함수를 호출할 때,

예제는 finish();를 호출해서 현재 창을 닫는다.

Using the linked page as an example, you should be able to do something like this:

WebAppInterface class

public class WebAppInterface {
    Activity mActivity;

    /** Instantiate the interface and set the activity */
    WebAppInterface(Activity activity) {
        mActivity = activity;
    }

    /** Finish activity from the web page */
    @JavascriptInterface
    public void finishActivity() {
        mActivity.finish();
    }
}

Now, in your activity you add the JS interface like this:

WebViewActivity

WebView webView = (WebView) findViewById(R.id.webview);
webView.addJavascriptInterface(new WebAppInterface(this), "Android");

And in your webpage, you can finish the activity by clicking a button, like this:

HTML Contents

<input type="button" value="Finish the activity now" onClick="finishActivity()" />

<script type="text/javascript">
    function finishActivity() {
        Android.finishActivity();
    }
</script>

[출처] http://stackoverflow.com/questions/20639476/calling-activity-function-from-separate-class