CODEWITHSUNDEEP
javascriptandroidandroid-webview
Amith Raravi
Amith Raravi

Reputation: 231

Android WebView - Javascript doesn't fire the call back function

I am new to Android and was trying to setup the Android Webview to load a javascript function and return the result to a callback function.

See the code below

public class AWebViewActivity extends Activity {

    /**
     * Defines an Interface to call Syntax Highlighting Javascript and return the result
     * to a string by calling the call back function.
     */
     public class JavaScriptInterface {
         Context mContext;
         JavaScriptInterface(Context c) {
             mContext = c;
         }

         //add other interface methods to be called from JavaScript
         // This annotation is required in Jelly Bean and later:
         @JavascriptInterface
         public void receiveValueFromJs(String str) {
              //do something useful with str
              Toast.makeText(mContext, "Received Value from JS: " + str,Toast.LENGTH_LONG).show();
         }
    }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Try WebView
        WebView webView = (WebView) findViewById(R.id.editor_view);
        //webView.setWebChromeClient(new WebChromeClient());

        webView.getSettings().setJavaScriptEnabled(true);

        // RiNxX's suggestion
        webView.setWebViewClient(new WebViewClient(){
            @Override
            public void onPageFinished(WebView view, String url){
                view.loadUrl("javascript:getValue()");
            }
        });

        webView.addJavascriptInterface(new JavaScriptInterface(this), "MyAndroid");
        webView.loadUrl("file:///mnt/sdcard/a.html");

        //SystemClock.sleep(1000);
        //webView.loadUrl("javascript:getValue()");
    }
}

The HTML file is given below:

<html>
    <head>
    </head>
    <body>
        <script type="text/javascript">
            function getValue()
            {
                var val="Amith Raravi";
                MyAndroid.receiveValueFromJs(val);
            }
        </script>
    Hey ya
    </body>
</html>

I have also added the INTERNET permission as a child of the Manifest element. I went through the other questions posted on StackOverflow and moved the script to Body of the HTML.

After i added the changes suggested by RiNxX, the app closes(it doesnt execute the callback) and i get the below warning in LogCat

JNI WARNING: jarray 0x405414e8 points to non-array object (Ljava/lang/String;)
I/dalvikvm(361): "WebViewCoreThread" prio=5 tid=9 NATIVE
I/dalvikvm(361):   | group="main" sCount=0 dsCount=0 obj=0x4051d580 self=0x29a1a8
I/dalvikvm(361):   | sysTid=370 nice=0 sched=0/0 cgrp=default handle=2728672
I/dalvikvm(361):   | schedstat=( 277421205 460097188 88 )
I/dalvikvm(361):   at android.webkit.BrowserFrame.stringByEvaluatingJavaScriptFromString(Native Method)
I/dalvikvm(361):   at android.webkit.BrowserFrame.stringByEvaluatingJavaScriptFromString(Native Method)
I/dalvikvm(361):   at android.webkit.BrowserFrame.loadUrl(BrowserFrame.java:246)
I/dalvikvm(361):   at android.webkit.WebViewCore.loadUrl(WebViewCore.java:1570)
I/dalvikvm(361):   at android.webkit.WebViewCore.access$1400(WebViewCore.java:53)
I/dalvikvm(361):   at android.webkit.WebViewCore$EventHub$1.handleMessage(WebViewCore.java:956)
I/dalvikvm(361):   at android.os.Handler.dispatchMessage(Handler.java:99)
I/dalvikvm(361):   at android.os.Looper.loop(Looper.java:123)
I/dalvikvm(361):   at android.webkit.WebViewCore$WebCoreThread.run(WebViewCore.java:629)
I/dalvikvm(361):   at java.lang.Thread.run(Thread.java:1019)
E/dalvikvm(361): VM aborting

I have been at it for over a day now. Any help would be most welcome:)

Upvotes: 2

Views: 9065

Answers (4)

LOG_TAG
LOG_TAG

Reputation: 20589

I'm having same issue, but worked fine when I try to load the file from assets:

webView.loadUrl("file:///android_asset/a.html");

Upvotes: 2

user1140237
user1140237

Reputation: 5045

java script Called from android webview

webView.loadUrl("javascript:setDatePickervalue(\""
                        + pselSelectedDateProp.getFormatedDate() + "\")");


Java Script Function

        <script type="text/javascript" language="JavaScript">
        function setDatePickervalue(selecteddate){          
                document.getElementById("text").innerHTML = selecteddate.toString();            
                //alert('hello' + selecteddate.toString());

            }
  </script>

.... i was trying to implement same thing like u did... its giving me vm aborting exception in emulator...BUT ITS WORKING FINE ON DEVICE..

Upvotes: 0

Amith Raravi
Amith Raravi

Reputation: 231

Apparently, this has been a long standing bug in the 2.3.3 emulator.

See the below link.

http://groups.google.com/group/android-developers/browse_thread/thread/992ca132e15745ec/da8da866d107e8b3?pli=1

Currently downloading 2.2 and 3.0 emulators.

Thank You for all the help, and the great forum.

I will be back with more questions!

Upvotes: 5

Sarim Sidd
Sarim Sidd

Reputation: 2176

Add webview client that calls javascript interface when page is loaded

webview.setWebViewClient(new WebViewClient() {
@Override    
public void onPageFinished(WebView view, String url) {    
   view.loadUrl("javascript:getValue()");    
}   
webview.loadUrl(SOME_WEBPAGE);

Upvotes: 1

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