I just got your problem.

Have a JS function like this.

function androidResponse() {

   window.cpjs.sendToAndroid(I am being sent to Android.);

}

Set up Android (Java).

Have a final class like this

final class IJavascriptHandler {

   IJavascriptHandler() {

   }



   // This annotation is required in Jelly Bean and later:

   @JavascriptInterface

   public void sendToAndroid(String text) {

      // this is called from JS with passed value

      Toast t = Toast.makeText(getApplicationContext(), text, 2000);

      t.show();

   }

}

Then on your WebView load have.

webView.addJavascriptInterface(new IJavascriptHandler(), cpjs);

Call JS function

webView.loadUrl(javascript:androidResponse();void(0));

UPDATED

Also I had a very bad time experiencing problems while passing hundreds of lines of string to JS from Java and I have subsequent post on StackOverflow with no good answers but finally resolved it knowing problme was of special characters inside string so take of special characters when you use string passing to and fro.

Passing Data From Javascript To Android WebView

HTML String Inside Nested String

HTML TextArea Characters Limit Inside Android WebView