Android/Webview: How to turn Observer pattern to a blocking function

Question

In a webview, I would like to wrap two things in one blocking function:

I have the following:

public class WebBikeWebView extends WebView {

  private String mData;

  public WebBikeWebView(Context context) {
    super(context);

    // result of loadUrl() returns here in this call-back, in message
    this.setWebChromeClient(new WebChromeClient() {
        @Override
        public boolean onJsAlert(WebView view, String url, final String message, JsResult result) {
            Log.d("LogTag", message);

            mData = message;

            result.confirm();
            return true;
        }
    });
  }


  // I would like to create a blocking method like this:
  public String getValue(final String name) {

    String code = "javascript:alert(' + " name + "')";

    this.loadUrl(code);

    ret = mData;   // problem is that mData is a result from the call-back onJsAlert()      

    return ret;
  }

} 

I would like the getValue() method to be a synchronous/blocking method.

It's a bit like using wait/notify on the same thread. I did tried wait/notify, but the control stops fetching the data as this interrupts the current thread.