How to get javascript value in Android

I am very new to Android and developing my first app. My Version is 6.0 and API veresion is 21.

My app is having a textbox and a button in its home page. I am putting my url and hit submit button so that a webview will loads this url.

In my url I included some javascript functions, they are defined to retuning some values.

I am trying to get that value and assign the value to other textbox.

I tried in two ways but none of them worked for me.

First
I created a new class as follows,

public class JsInterface {
private String val;

@JavascriptInterface
void receiveString(String value) {
    Log.d("This is what from JS-", value);
    val = value;
}
String Val() {
    return val;
}

}

My JS function

function goAndroid(Go Value to Script){ 
    var goString = "Hello " + Go Value to Script; 
    window.MyAndroidApp.receiveString(goString); 
} 

In mainActivity.java

WebView.addJavascriptInterface(new JsInterface(), "MyAndroidApp"); 
WebView.loadUrl("javascript:goAndroid('Go Value to Script')") 
//Below value is null.. 
System.out.println(new JsInterface().Val()); 

Here the system out comes nothing...

Second
As I am using API version 21, I followed the another way,

webView.evaluateJavascript("(function() { return goAndroid('My Value'); })();", new ValueCallback() { 
    @Override 
    public void onReceiveValue(String s) { 
    Log.d("LogName--------------", s); 
} 
}); 

Here I am getting a small popup which says " unfortunately, app has stopped". In LogCat I am getting the following error

05-10 17:36:13.922: E/AndroidRuntime(822): FATAL EXCEPTION: main 05-10 17:36:13.922: E/AndroidRuntime(822): java.lang.NoSuchMethodError: android.webkit.WebView.evaluateJavascript 05-10 17:36:13.922: E/AndroidRuntime(822): at com.example.asdf.MainActivity$5.onClick(MainActivity.java:209)

Thanks in advance.

— modified on May 10, 2016, 2:51:39 PM

Ashish Tripathi

As form the log the method is not there. Check the name for once may be you are using some different method name.

This is webView's method. I double checked it. I typed webview and then dot then I used ctrl+space to get available methods and selected evaluateJavascript .