lexanderA » Adding alert() support to a WebView

Jan 27 2009

Adding alert() support to a WebView

Category: Android, JavaScript, WebView examples — Aleksander Kmetec @ 9:54 pm

As promised earlier, here is an example of how to add support for alert() function to a WebView in your Android application:


final WebView browser = (WebView)findViewById(R.id.browser);
/* JavaScript must be enabled if you want it to work, obviously */
browser.getSettings().setJavaScriptEnabled(true);

final Context myApp = this;

/* WebChromeClient must be set BEFORE calling loadUrl! */
browser.setWebChromeClient(new WebChromeClient() {
    @Override
    public boolean onJsAlert(WebView view, String url, String message, final android.webkit.JsResult result)
    {
        new AlertDialog.Builder(myApp)
            .setTitle("javaScript dialog")
            .setMessage(message)
            .setPositiveButton(android.R.string.ok,
                    new AlertDialog.OnClickListener()
                    {
                        public void onClick(DialogInterface dialog, int which)
                        {
                            result.confirm();
                        }
                    })
            .setCancelable(false)
            .create()
            .show();

        return true;
    };
});

/* load a web page which uses the alert() function */
browser.loadUrl("http://lexandera.com/files/jsexamples/alert.html");

Code for adding support for confirm() and prompt() is almost identical and can be found in Mosembro’s source code.

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Tags: Android, JavaScript, WebChromeClient, WebView

Comments (9)

9 Responses to “Adding alert() support to a WebView”

Sikus (April 9th, 2009 at 11:11 am )

Hello, I try your code, but I don’t see the alert when I click on the link. First alert is showing. Is there any bug?
alex (April 9th, 2009 at 11:39 am )

Hi! I’m not sure what the problem could be. I compiled the example code again and it works for me on Android – the alert() shows up on every click. But it is true that it didn’t work in Firefox. I changed the demo HTML page a bit so that the alert dialog is now called from the onclick event. Can you try it again to see if it works?
Sikus (April 29th, 2009 at 1:27 pm )

Thanks alex,
now, in Firefox, the page work correctly. But I have still problem in my one project and i don’t know where is problem. But when I try it in new project, everything work all right. Thank you very much.
Sikus (May 13th, 2009 at 4:26 pm )

Hi, I have this code:
@Override
public boolean onJsAlert(WebView view, String url, String message, final android.webkit.JsResult result) {
// some code to start new Activity
startActivity(i);
return true;
};
My link :
s += “” + “text“;

webview.loadDataWithBaseURL(null, ” ” + “” + “Title” +
+ “” + “” + s + “”
+ “”, “text/html”, “UTF-8″, “about:blank”);

So when I clik to the link on displej (with my finger) new Activity is open. It is all right. But when I use trackbol it open webbrowser. Why?
Aleksander Kmetec (May 14th, 2009 at 7:08 pm )

Unfortunately, I don’t know the answer to your question. I did some quick tests and I can’t get clicking with trackball to behave differently from clicking with your finger. Perhaps developers on one of Android mailing lists will be able to help you out: http://developer.android.com/community/index.html
Sikus (August 28th, 2009 at 11:10 am )

Hi. I have still problem with scrolling. When I click on the link and alert return true, web page scroll top. I can forbid this scroll. Is there any solution? Can I react after the metod onJsAlert end?
paul (September 9th, 2009 at 11:33 am )

Hi, I saw this on the apps-for-android repo as well, works perfectly.
What I would need is to do it with WebChromeClient instead of WebViewClient — the two are very similar but the former doesn’t have the onJsAlert.
Any ideas?
Aleksander Kmetec (September 9th, 2009 at 3:09 pm )

@paul: take a closer look. The example already uses a WebChromeClient which does have onJsAlert. :)
paul (September 11th, 2009 at 10:54 am )

Sorry, I mean WebViewClient instead of WebChromeClient …