get value form Android function that is call in javascript and return it to js

Question

I have tried this code and stuck form many days.
Actually waht i want is to integrate mathjax library for mathametics formula and to get output form it.

 <html>
<head>
<style>
body{
background-color: #FA5858;
color:#fff;
}
input{
background-color: #F7D358;
width: 300px;
padding:10px;
color: #000;
}
div#content{
padding:20px;
background-color: #F7D358;
color: #000;
}
</style>
<script type="text/javascript"  src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">

    function showAndroidToast(toastmsg) {
        var x= Android.showToast(toastmsg);
        return x;
    }

function testcall(toastmsg){
 alert(showAndroidToast(toastmsg));
}
</script>
</head>
<body>
<center>
<h3>Binding JavaScript code to Android code</h3>
<div id="content">

</div>
<div>
Here are few examples: 
When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are
$$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$
</div>
<div>
<input type="button" value="Make Toast" onClick="testcall('Toast made by Javascript New:)')" /><br/>

</div>
</center>
</body>
</html>

And this in my android code

    public class WebAppInterface {
    Context mContext;

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

    /**
     * Show Toast Message
     * @param toast
     */
    public String showToast(String toast) {
        Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
        String test="\\hspace1ex \\color{blue} {Simplify:} \\hspace1ex 2x(3x+2xy)";
        return test;
    }
    }

But my android code doesn't return any vaule to javascript function.
Any help is appreciated.

Like ,

this is my android function

   public String showToast() {

    String test="\\hspace1ex \\color{blue} {Simplify:} \\hspace1ex 2x(3x+2xy)";
    return test;
}

and in javascript i want the value that is return by this showToast() function

Thanks

How do you init your Webview? Please post a little bit more code :) — Patrick Dorn
– Patrick Dorn, Commented Apr 2, 2015 at 10:06

Patrick Dorn · Accepted Answer · 2015-04-02 09:28:49Z

1

This is what i did in an App:

Set up the Webview:

  final WebView webView = new WebView(context);
  webView.getSettings().setJavaScriptEnabled(true);
  webView.addJavascriptInterface(new WebViewInterface(), "Android");
  webView.loadUrl("file:///android_asset/web/page.html");

with this WebViewInterface implementation:

import android.webkit.JavascriptInterface;

public class WebViewInterface {

    @JavascriptInterface
    public void log(String text) {
       Log.d("TAG", text);
    }
}

The page.html is located in the assets/web folder and looks like this:

<!DOCTYPE html>

<html>
<head>
    <script language="javascript" src="script.js">  </script>
</head>
<body>
</body>
</html>

The script.js file is located in the assets/web folder too:

function logText(text) {
    Android.log(text);
}

function toBeCalledFromAndroid(text) {
    // Do something in javascript
}

The logText function from javascript calls the Navive log method in Android.

To call a Javascript function from native Android code you have to do the following:

String loadingUrl = "javascript:toBeCalledFromAndroid('" + text + "')";
webView.loadUrl(loadingUrl);

edited Apr 2, 2015 at 9:28

answered Apr 2, 2015 at 8:42

Patrick Dorn

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5 Comments

ADT Over a year ago

Thanks for your reply .. But what i want is to pass string form WebAppInterface function and get its value in javascript

ADT Over a year ago

@ PaMADo u misunderstand my question..can u tell me how i ll get string form interface to javascript? have a look i have updated my question..

Patrick Dorn Over a year ago

This should show a toast in your example: String loadingUrl = "javascript:showAndroidToast('" + text + "')"; webView.loadUrl(loadingUrl);

Patrick Dorn Over a year ago

This could help you: codelixir.com/…

ADT Over a year ago

Thank .. i ll go through it.. and let u know

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