Develop Reference

Is there a way to convert Javascript alerts to show as Toast in Android WebView?

I have a web app thats working with Javascript alerts on most pages. Now I have recently created a WebView application for the same app. The app works fine, the alerts show.
I've seen solutions that suggest binding JavaScript code to Android code and then call these methods for example to show toast.
I have no doubt that this works, but now, for me, this means I'd have to re-write the code(s) that trigger these alerts.
My question is, is there a way to automatically capture all the alerts and display their contents as toasts instead?

You can use a WebChromeClient:
https://developer.android.com/reference/android/webkit/WebChromeClient
Create an instance of it, set it to your webview, and override onJsAlert.
Be sure to read the docs, to return the correct value, so it doesn't show the javascript alert also.

Thanks to Moonbloom's answer and this answer also.I managed to come with a solution that works exactly as I wanted. So for anyone who will stumble upon the same issue in the future, the snippet below is for you:
mWebView.setWebChromeClient(new WebChromeClient() {
#Override
public boolean onJsAlert(WebView view, String url, String message,
final JsResult result) {
Toast.makeText(getApplicationContext(), message, Toast.LENGTH_LONG).show();
result.confirm();
return true;
}
});
Where mWebView is a WebView instance.

Listen for URL fragment id change in WebView

It seems that the WebViewClient methods such as shouldInterceptRequest(), onPageStarted(), and shouldOverrideUrlLoading() only listen for URL changes that cause the WebView to load a new page. Is there a way to detect URL changes for fragment IDs, i.e. index.html#fragment_id, on a WebView?

I know that this is a really old question but i found out a solution that isn't available anywhere in Stack Overflow. jpetitto's answer works but it messes up javascript if we use hash change for routing or other such features.
I found out that by overriding the method doUpdateVisitedHistory in WebViewClient we can catch url's on hash change. Do see below snippet for example.
mWebView.setWebViewClient(new WebViewClient() {
#Override
public void doUpdateVisitedHistory(WebView view, String url, boolean isReload) {
super.doUpdateVisitedHistory(view, url, isReload);
// somecode to run on hash change.
}
}
Note: this method is fired on hash change and url change.

As mitvenkatesan described in his comment to the question, this can be achieved by overriding the window.onhashchange() event of the page inside the WebView.
It turns out that this solution has already been addressed in another question.

Android longpress not being passed to webView as oncontextmenu event

My app is designed to be used outdoors (yachting) and displays a web page in a WebView (so I can use all the display area, fix in landscape, disable extraneous inputs like the BACK_KEY etc.).
In the web page, I want to capture the oncontextmenu event on an image like:
<img src="start_line_pin.png" width=55px
id="pinButton"
oncontextmenu = 'startLinePress("PIN"); return false'\>
When I open the page in my app's webview, a long press doesn't fire the event. Android doesn't seem to be passing the longpress event to the web page.
If I open the page directly in Chrome, my startLinePress function is called with a long press as I intended.
So, can anyone suggest how I get the longpress to be passed into the HTML in my WebView instead of it being handled by Android?

One of the most beneficial features of a forum such as this is that it makes you really think about your problem from another point of view.
The answer to my problem lies in the fact that I was trying to use an undocumented feature - the longClick on the web page invoking the oncontextmenu event.
The answer is to use the onLongClick event in java and then pass the event to the javascript function by using the WebView.loadUrl method. My WebView is contentView and the javascript function is javascript:startLinePress as follows:
contentView.setOnLongClickListener(new OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
WebView.HitTestResult hr = ((WebView)v).getHitTestResult();
if(hr.getType() == 5){
contentView.loadUrl("javascript:startLinePress(\"ACTIVITY\")");
}
It needs a little more work to identify which element was clicked, by examining hr.getExtra() but you get the general idea.
Thanks stackoverflow for the great forum.

Disable page forwarding in Android webview

I have a webview that shows ads (not my ads), the problem is when user clicks the "x" button to exit the ad, the ad still directs them to a site. What I wonder is since I can't control the ads, can I instead Disable page directing/forwarding inside webview? that means even if user clicks a link inside my webview nothing should happen.

You are looking for WebClient.shouldOverrideUrlLoading method.
webview.setWebViewClient(new WebViewClient() {
public boolean shouldOverrideUrlLoading (WebView view, String url){
//True if the host application wants to leave the current WebView and handle the url itself, otherwise return false.
return true;
}
});

I tried using shouldOverrideUrlLoading, but it didn't work. It looks like that this method is called only once when the html is loaded. After that, you click a link but the method is no more invoked.
I am also making a WebView embedding Youtube Player. Instead of forwarding ads redirect from the WebView, I prefer to open ads in a browser. So I override onLoadResource method:
#Override
public void onLoadResource(final WebView view, final String url) {
if(url.indexOf("googleadservices.")>-1){
view.getSettings().setJavaScriptEnabled(false);
view.stopLoading();
view.postDelayed(
new Runnable(){
#Override
public void run(){
Uri uri=Uri.parse(url);
Intent i=new Intent(Intent.ACTION_VIEW,uri);
i.setClassName("com.android.browser","com.android.browser.BrowserActivity");
startActivity(i);
}
}
,100
);
}
}
It worked. When I clicked the ads link, a new browser is opened in which ads site is displayed well, and the WebView was not redirected. When I push the return button, WebView show up again and I can continue watching video.
But there were still problems. If I repeat opening browser and returning to WebView for many times, the WebView might fail to block redirecting to the ads site. It is just redirected to the ads site. If I am lucky I could repeat opening and returning for 100 times. But sometimes It failed just when I repeat several times. I don't know why.
Does anyboday have any idea about how to improve it? Or is there another way to disable ads redirect?

You can build undetected webview build-id adblocker
I know it is too late for answering this question, however, for the sake of others who have the same question.
Well, you can build webview build-id adblocker, if you wish to prevent ads from loading, and provide smooth experience to the users, I am confident, because I have already implemented it in may app.
The Idea
Is to have a black list of all possible ad-serves domain name, then while webview load resources, you will prevent loading from black list domains. so it depends on how many ads-serves domain you have in the black list, fortunately, there is one website (pgl.yoyo.org/as/) which provide you with a very long list of ad-serves domai names, and listed them in many flavoures.
you can read this article for:
how to implement webview build-id adblocker
, you will build it %100 as long as you follow step by step instructions.
A summary of what we need to do:
Get the list of ad hostnames from pgl.yoyo.org.
Save the list somewhere, load it when application starts.
UseWebViewClient.shouldInterceptRequest(WebView, String) to intercept
requests.
Check if the request URL belongs to one of the hostnames in
the list and override it, returning a dummy resource instead of the
actual one, which is supposed to be ads

Button in a webview without Javascript

I have an android application that loads a webview from a server. I do not have the server code so I cannot change anything in Javascript. I want to figure out when a button is being clicked in a webview and what is the label in the button. I do not know the Id, I just want to get the label.
I tried searching for this but could not find an answer. I found solutions where you can work in the javascript but in my case I cannot.

This suggestion may help to find useful information that could lead to determination of your button label. Override shouldOverrideUrlLoading(), shouldInterceptRequest() and/or onLoadResource() for the WebViewClient so you can get at the URL of any redirects.
Example:
webview.setWebViewClient(new WebViewClient() {
public boolean shouldOverrideUrlLoading(WebView view, String url) {
// Try to learn something useful from the 'url' here.
// Continue as normal, loading the 'url' within this WebView.
view.loadUrl(url);
return false; // Allow the WebView to handle the request.
}
// Optional: Add similar for "shouldInterceptRequest()" and/or "onLoadResource()".
});
Note: Overriding shouldOverrideUrlLoading() as above is the standard way to keep redirects within the same WebView rather than redirecting to the default browser application.

You might really want to check this page:
Building Web Apps in WebView (Google API Guides)
Specifically, it seems that addJavascriptInterface might be what you are looking for:
addJavascriptInterface(Object object, String name)
It allows you to execute your Java code from javascript and, paired with the ability to insert code in a page, it's an incredibly powerful tool for granting you a high level of coupling between your Activity and your page.
I think that at this point you will already know what to do, but I'll sketch a possible course of action anyway:
create a javascript interface with the callbacks you want executed in your activity when a button is pressed
as soon as your page loads, install the code to call your javascript interface in each button (or link) by injection
Hope this helps