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WebView - only show back button if back history exists

I developed a simple webview app. I added a button which should act as the back button, so users can navigate back one page.
The button is initially hidden and should only show if a back history exists.
How can I realise this?
The code is simple:
backButton = findViewById(R.id.backButton);
backButton.setEnabled(blizzView.canGoBack());
but where do I have to call this? How is the "some site loaded" event called?
Update:
I tried to apply #Murats answer, but nothing happens:
private WebView blizzView; // my webview
private Button backButton;
public void onPageFinished(WebView view, String url)
{
backButton = findViewById(R.id.backButton);
backButton.setEnabled(blizzView.canGoBack());
if (blizzView.canGoBack()) {
backButton.setVisibility(View.VISIBLE);
} else {
backButton.setVisibility(View.INVISIBLE);
}
}

You can use WebView#canGoBack to find out if there is a backstack. You can check for that after the page is loaded e.g. in WebViewClient#onPageFinished

It works like this:
blizzView.setWebViewClient(new WebViewClient() { //
#Override
public void onPageFinished(WebView view, String url) {
super.onPageFinished(view, url);
backButton = findViewById(R.id.backButton);
backButton.setEnabled(blizzView.canGoBack());
if (blizzView.canGoBack()) {
backButton.setVisibility(View.VISIBLE);
} else {
backButton.setVisibility(View.INVISIBLE);
}
}
});

Webview activity not showing anything on second load

I have this weird problem when showing an activity which consists (only) out of a webview.
The first time I start this Activity B by clicking on something in activity A, B is properly loaded and functional. I press the return button, go back to A, then click on the same button to go to B and my webview doesn't show anything. Debugged it tons of times and nothing seems out of the ordinary. There are also no crashes in the stack trace log... This problem by the wway occurs always in debug mode and only sometimes in run mode.
Here is the code for the activity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_spin);
myItem = (Item) getIntent().getSerializableExtra("Item");
initView();
initHandlers();
}
private void initView()
{
webView = findViewById(R.id.webview_spin);
//TODO : webViewClient vs webChromeClient ?
webView.setWebViewClient(new WebViewClient());
webView.setWebChromeClient(new WebChromeClient());
webView.getSettings().setJavaScriptEnabled(true);
String json = new Gson().toJson(myItem);
webView.loadUrl("file:///android_asset/item.html?item="+json);
}
private void initHandlers()
{
OrientationEventListener orientationEventListener = new OrientationEventListener(this) {
#Override
public void onOrientationChanged(int orientation) {
webView.reload();
}
};
orientationEventListener.enable();
}
FYI this problem occured before setting the orientationlistener.

That looks like somehow the render process of the WebView is failing. You could store the WebViewClient you created on a variable and check the result of its method onRenderProcessGone() to check if it is rendering the second time you load the activity. Here you have all the WebViewClient methods: https://developer.android.com/reference/android/webkit/WebViewClient

Redirecting from webview to java activity

I have a registration page in web view which I am using in an Android application, after successful registration it should redirect intent which is not webview. Is it possible to do so? And if possible are there any suggestions for doing this?
My project is in Eclipse.

Show the alert in webview and get this done as below as there is a callback (onJsAlert) when any alert is shown.
private void loadWebViewStuff() {
myWebView.setWebChromeClient(new MyWebChromeClient());
myWebView.loadUrl(URL);
}
final class MyWebChromeClient extends WebChromeClient {
#Override
public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
//"message" is what is shown in the alert, here we can do whatever with it
}
}

Android listener for webpage to start loading?

I have a simple webview that loads a website. Once the website is loaded, I have the following to focus/scroll to the login box:
mWebview.setWebViewClient(new WebViewClient(){
#Override
public void onPageFinished(WebView view, String url) {
// TODO Auto-generated method stub
super.onPageFinished(view, url);
mWebview.scrollTo(681, 100);
(I've heard that onPageFinished is deprecated, but it's working for me in 2.2>4.4, so I'm just leaving it for now.
Anyway, I would like some sort of way to monitor for when the user actually logs in, that way when the page is done loading for the second time, I can then call some js and forward them to another page, but I have no idea how to do that. :(
I can just do another onPageFinished after they log in, but I don't know how to start monitoring... In other words, I can't start another onPageFinished immediately after the current, because it just redirects automatically.
Does anyone have any suggestions? I would greatly appreciate it! :)
EDIT:
Here's the entirety (minus the import headers) of my MainActivity.java class.
public class MainActivity extends Activity {
private WebView mWebview ;
#Override
public void onBackPressed() {
if(mWebview.canGoBack() == true){
mWebview.goBack();
}else{
super.onBackPressed();
}
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mWebview = new WebView(this);
mWebview.getSettings().setJavaScriptEnabled(true); // enable javascript
mWebview.getSettings().setBuiltInZoomControls(true);
if(android.os.Build.VERSION.SDK_INT >= 11) {
mWebview.getSettings().setDisplayZoomControls(false);
}
final Activity activity = this;
mWebview.setWebViewClient(new WebViewClient() {
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
Toast.makeText(activity, description, Toast.LENGTH_SHORT).show();
}
});
mWebview .loadUrl("http://example.com");
setContentView(mWebview );
mWebview.setWebViewClient(new WebViewClient(){
#Override
public void onPageFinished(WebView view, String url) {
// TODO Auto-generated method stub
super.onPageFinished(view, url);
mWebview.scrollTo(681, 100);
}
}
);
}
I think I might be missing a curly bracket, but ignore that for now, haha. So anyway, after mWebview.scrollTo (the last line), the webpage is done loading, and it just chills at the login page. After a user logs in, the page (obviously) starts to load and directs to another post-login URL. I'd like to check the URL with an if statement after the page is done loading for the second time.
Does that make more sense? Sorry, it's confusing me too, trying to explain it.

Usually there will be two separate URLs, one for the post log-in page and one for the pre log-in page. You can have an if statement that checks the URL to make sure you've logged in, and if you have, then it redirects/closes/whatever.
I had a similar issue here:
Closing a Webview in Android
So basically you just want to execute some JavaScript once you've logged in? I don't see why you can't have an if statement to check whether you're logged in or not, and if you're logged in, then execute the js.
Something like this maybe?
wv.setWebViewClient(new WebViewClient() {
#Override
public void onPageFinished(WebView view, String url) {
if (url.contains(getString(R.string.loginURL))){
super.onPageFinished(view, url);
mWebview.scrollTo(681, 100);
}else if(url.contains(getString(R.string.loggedInURL))) {
wv.loadUrl(js goes here);
}
}
}
This will execute every time a page is finished loading in your WebView

Creating An In-Game Web Browser on Android

In my game, I'd like to have a kind of "message of the day" feature. Basically, when the user taps the "message of the day" button in the main menu, it would open up a browser view in-game. When the user is done, he taps a "close" button and the view disappears, returning him to the game menu.
So, is it possible to create a browser view dynamically? If yes, how?

The following can be used in a Dialog as well
public void setWebView() {
//WebViewClient is used if you want to capture stuff from the webview, like if a link was pressed
WebViewClient yourWebClient = new WebViewClient() {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
open_web = true;
if (!url.startsWith("http://") && !url.startsWith("https://")) {
url = "http://" + url;
}
Intent browserIntent = new Intent("android.intent.action.VIEW",
Uri.parse(url));
startActivity(browserIntent);
return true;
}
};
WebView wv = (WebView) findViewById(R.id.webview);
wv.setWebViewClient(yourWebClient);
String str = getHtml();
wv.loadData(str, "text/html", "utf-8");
wv.setBackgroundColor(0);
}
boolean isAsset = false;
private String getHtml(){
InputStream source = null;
if (isAsset){
source = getAssets().open("motd.html");
} else {
source = new FileInputStream(Environment.getExternalStorageDirectory() + "motd.html");
}
}

You could probably just use a WebView. When you want it to show up you could just set its view state to View.VISIBLE. When you want it to go away, just set its view state to View.GONE.

You can add/remove a WebView to your game dynamically (or show/hide it, whatever you prefer).
Take a look at the WebView tutorial for more info:
http://developer.android.com/resources/tutorials/views/hello-webview.html
Make sure to leave room for your "Close" button in your layout, i.e. you don't want to set the layout height to "fill_parent".