[android-developers] How to get javascript value in Android

[Raja R]

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.

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