How to get return value from javascript in WebView of Android?

Same as Keith but shorter answer

webView.addJavascriptInterface(this, "android");
webView.loadUrl("javascript:android.onData(functionThatReturnsSomething)");

And implement the function

@JavascriptInterface
public void onData(String value) {
   //.. do something with the data
}

Don't forget to remove the onData from proguard list (if you have enabled proguard)

Here's a hack on how you can accomplish it:

Add this Client to your WebView:

final class MyWebChromeClient extends WebChromeClient {
        @Override
        public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
            Log.d("LogTag", message);
            result.confirm();
            return true;
        }
    }

Now in your javascript call do:

webView.loadUrl("javascript:alert(functionThatReturnsSomething)");

Now in the onJsAlert call "message" will contain the returned value.