We Keep Coding

How can I show a confirm dialog with Vaadin 23 when the user clicks on back button?

how can I show a dialog to stay or leave the current page with Vaadin 23, when a user clicks back button on browser?
Regards

It depends what you wish to achieve.
See this older discussion: Vaadin onbeforeunload event
Generally: use the onBeforeUnload javascript even for this
https://www.w3schools.com/tags/ev_onbeforeunload.asp
This is executed when the user would go away from your vaadin app, but not when using the back button inside your vaadin app.
For these you can use the navigation lifecycle events as documented here
https://vaadin.com/docs/latest/routing/lifecycle
Not sure if it also catches, when a user leaves your app...

Assuming you mean, that is it possible to prevent the navigation happening, you simply can't do that. If disabling back button is important for you, the only way is to enforce your users to use the application via desktop shortcut which starts the app using --app paramater (if using Chrome). This is not a limitation in Vaadin, but a general restriction in browser behavior.

There is already a possibility to handle Browser Back Button Event on Vaadin (https://vaadin.com/docs/v14/flow/routing/tutorial-routing-lifecycle):
public class SignupForm extends Div implements BeforeLeaveObserver {
#Override
public void beforeLeave(BeforeLeaveEvent event) {
if (this.hasChanges()) {
ContinueNavigationAction action = event.postpone();
ConfirmDialog.build("Are you sure you want"+
" to leave this page?")
.ifAccept(action::proceed)
.show();
}
}
private boolean hasChanges() {
// no-op implementation
return true;
}
}
This code works once but when you click on Cancel on Confirm Dialog so that you want to stay on current page and click again on Back Button on Browser, than you don't see any Confirm Dialog again... I can not understand, why...

Android studio-java focus on listitem doesn't work

I'm trying to reverse engieering a Dialer from a 4.4.4 android device.
I added a onkeydown listener ,so when the user press the '9' button,the listview in the callLogActivity should scroll to top.
Of course I'm editing the smali files,not the java itself,but I'll attach a java code of everything I tried,which didn't give the desired result
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getKeyCode() == 16) {
listview.requestFocus();
listview.setSelection(0);
listview.setSelectionAfterHeaderView();
listview.setItemChecked(0, true);
return true;
return super.dispatchKeyEvent(event);
}
}
As you can see,I tried many similar methods, such as setSelection() and setItemChecked() and more....
Actually,The list indeed scrolls to top,but the focus(selected) still stay on the current ListItem..
It's not just a visual effect problem,the focus really stay on the current item(you can see it when you just hit the "ok" button).
If you were wondering what's the meaning of "pressing the ok or '9' button" ,it's the time to expose that device model, it's the xiaomi qin 1s,a feature phone with android OS on it.
Did i miss something?

Android Application for Kids

I'm Developing Android Application for Parental Controlling, so I want to disable home and back button. Because kids are unpredictable, their can push home button or back button and so on. Than i want to disable sliding notification bar. (Because notification bar can change device configuration and setting)
I'm planning to create Android Application which is similar to the Samsung Kids Mode-Parental Control.
Is possible to create application like Samsung Kids Mode? Can you give some link/article or even example program to me?
I Have tried this :
#Override
public void onAttachedToWindow() {
this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
super.onAttachedToWindow();
}
but it not handle home button, the Home button still working.
Thanks in advance to everyone for taking time to read this, hoping a positive solution.

I dont know of anyway to override the home button. Im not sure that it can be done. You can override the back button like so.
#Override
public void onBackPressed() {
//do nothing, important dont call super.onBackPressed
}
Another this you can do is set the app to immersive mode to reduce the chance of accidently exiting the app
https://developer.android.com/training/system-ui/immersive.html

Extended from Activity
#Override
public void onBackPressed() {
}
can be used to override back button. Be sure to remove super.onBackPressed().

Prevent back button after logout in android

After logout the user is directed to login screen in android. Now, if user clicks on back button of phone it should stay on login screen itself.
How can I make it possible in android?
I have used following code in my application but it will close my application. It should stay on the login screen only
Intent objsignOut = new Intent(getBaseContext(),Hello.class);
objsignOut.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(objsignOut);
Please guide me the correct way.

override the onBackPressed in your login activity, to do nothing..
public void onBackPressed() {
//do nothing
}

It seems to me that there are simpler and cleaner solutions than overriding onBackPressed method, as mentioned here and here.
You can provide flags when launching a new activity (on login or logout) to simply clear the "back-stack" rather than override the behavior for the back-button:
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
This is a safer solution that can also be used after you log-in and not just after you log-out.

public void onBackPressed(){
if(appCanClose){
finish();
}
}
These functions can exist in both the system framework (used if not in your code), as well as in your code. If you leave it empty, the app will do nothing when the back button gets pressed.
In this example, when the boolean value appCanClse is true, the back button will quit the app, if false, the back button wil do nothing. I would make sure the user still has someway to quit the app. :p

You can do it by just adding this two line of codes
#Override
public void onBackPressed(){
moveTaskToBack(true);
}
It will prevent going back to previous activity as well as take the app to background when anyone hits back button

The actual solution is
#Override
public void onBackPressed() {
super.onBackPressed();
finishAffinity();
}
add this code in Login Activity. App closes when back button clicked in login page.

In GWT, how to reset the URL when the user hits "Cancel" in the navigation confirmation dialog?

In my GWT application, I want to ask a user confirmation when he navigates out of the current application, i.e. by entering a URL or closing the browser. This is typically done by registering a ClosingHandler and setting the desired dialog message in the onWindowClosing method. This seems to work well.
However, if the user tries to navigate say to http://www.gmail.com (by typing it in the URL bar) and hits Cancel to indicate he doesn't want to navigate, then my app keeps running but the browser's URL bar keeps indicating http://www.gmail.com. This causes a number of problems later in my application and will give the wrong result if the user bookmarks the page.
Is there a way to automatically reset the URL when the user presses Cancel?
Or, alternatively, is there a way to detect the user pressed the Cancel button? If so, is there a way to set the URL without triggering a ValueChangeEvent? (I could add some logic to prevent this, but I'd rather use a built-in mechanism if it exists.)

Not sure if this works but did you try: History.newItem(History.getToken(), false); to reset the URL? It does set the history token without triggering a new history item.

I managed to do this. It looks like GWT DeferredCommand are executed after the confirmation window has been closed. This, combined with Hilbrand's answer above, give me exactly what I want. Here is exactly what I do:
public final void onWindowClosing(Window.ClosingEvent event) {
event.setMessage(onLeaveQuestion);
DeferredCommand.addCommand( new Command() {
public void execute() {
Window.Location.replace(currentLocation);
}
});
}
Where currentLocation is obtained by calling Window.Location.getHref() every time the history token changes.

I solved this by creating a custom PlaceController and replacing the token in the url. Not an ideal solution but it works!
if (warning == null || Window.confirm(warning)) {
where = newPlace;
eventBus.fireEvent(new PlaceChangeEvent(newPlace));
currentToken = History.getToken();
} else {
// update the url when user clicks cancel in confirm popup.
History.replaceItem(currentToken, false);
}