JavascriptInterface Method for WebView not called

Question

I have a very weird problem, my application is an e-reader. to call functions for the web view I use a JavaScript class:

    public class MyJavaScriptInterface {
        Context mContext;

        /* Instantiate the interface and set the context */
        MyJavaScriptInterface(Context c) {
             mContext = c;
        }

        @JavascriptInterface
        public void functionToCall(String input) {
             System.out.println("this function was called: "+ input);
        }
  }

I have a customized web view where I add my JavaScript class.

  public class newBTWebView extends WebView implements {
       public newBTWebView(Context context) {
         super(context);
         init(context);

       }
       public void init(Context context) {
         System.out.println("newBTWebview init");
         this.context = context;
         this.getSettings().setJavaScriptEnabled(true);
         setInitialScale(100);
         addJavascriptInterface(new MyJavaScriptInterface(this.context), "HTMLOUT");
     }
 }

and in my main activity I initiate the web view and call the function using JavaScript:

   public class BookReader extends Activity implements WebViewDelegate{
        private static Context mContext;
        private static newBTWebView testWV;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        System.out.println("onCreate");
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        super.onCreate(savedInstanceState);
        testWV = (newBTWebView) findViewById(R.id.mywebview1);
        testWV.setDelegate(this);
        testWV.setWebChromeClient(new WebChromeClient());
        testWV.getSettings().setJavaScriptEnabled(true);
        testWV.getSettings().setPluginState(PluginState.ON);


        testWV.setWebViewClient(new WebViewClient() {

             @Override 
             public boolean shouldOverrideUrlLoading(WebView view, String url)
             {
                 System.out.println("shouldOverrideUrlLoading: " + url);
             }
             @Override
             public void onPageFinished(WebView view, String url) {
                 System.out.println("onPageFinished");
             }
         }
    }
    public void callMyFunction
    {
         System.out.println("callMyFunction");
        testWV.loadUrl("javascript:window.HTMLOUT.functionToCall('myinput');”);
    }
 }

The functionToCall was working perfectly, lately in my latest update, as I was testing the application on the device it was still working, but when I submit it on store the functionToCall was not getting called any more. I tested the apk file on the device the functionToCall is not getting called. It only works when I run the app directly from the pc to the device, but using the apk file on the same device as mentioned before the functionToCall doesn't get called.

I have tested on Samsung S4, Samsung Note 10.1, and nexus note. with android 4.4.2, 4.0.4 and 5.0.1.

Answer 1

Have you enabled proguard or some code obfuscation ?if yes you should add keep attributes

-keep public class com.MyJavaScriptInterface 
-keep public class * implements  com.MyJavaScriptInterface 
-keepclassmembers class * implements com.MyJavaScriptInterface {
<fields>;
<methods>;
}

i do not know your classes full qualified names. so please put your fully qualified names.