Question

In my Android web app I am trying to use javascript (from a remote HTML file) to control the visibility of an Android WebView.

I have attempted to use the addJavascriptInterface class with no success. (see http://developer.android.com/guide/webapps/webview.html)

Essentially I would like my javascript to be the following

<script>
function this() {
  Android.hideView('myWebViewID');
}
window.onload = this;
</script>

Seems like it would be easy, yet all my attempts cause my app to crash during debugging.

My latest attempt was something along these lines:

public class JavaScriptInterface {
    Context mContext;
    JavaScriptInterface(Context c) {
        mContext = c;
    }
    public void hideView(View v) {
        WebView webview_x = (WebView) v;
        webview_x.setVisibility(View.GONE);
    }
}

Answer 1

The problem is that you are casting the string “myWebViewID” in a WebView object.
I guess this is impossible.

To do what you want, you have to implement something like a switch that convert the string you use in JS to an ID (int) that identifies your WebView:

public class JavaScriptInterface {
    private Activity mContext;

    JavaScriptInterface(Activity c) {
        mContext = c;
    }

    public void hideView(String v) {
        int id = stringToId(v);
        WebView webview_x = (WebView) mContext.findViewById(id);
        webview_x.setVisibility(View.GONE);
    }

    private Integer stringToId(String str) {
        if(str.equals("stringForId1") {
            return R.id.webView1;
        } else if(str.equals("stringForId2") {
            return R.id.webView2;
        } else if(...) {
          ....
        } else {
            return null;
        }
    }
}