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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...

Set Authentication while DeviceAdmin mode get disable?

I am create an parental control app, where i want to put the Simple password authentication before disable to administrator mode by used . I am using DeviceAdminReceiver . An Idea or sample code which help . Thankyou

Unfortunately there is no direct approach to achieve it. However there is a workaround which can be done by overriding onDisableRequested() method of DeviceAdminReceiver
public class AdminReceiver extends DeviceAdminReceiver {
#Override
public CharSequence onDisableRequested(Context context, Intent intent) {
DevicePolicyManager mDPM =(DevicePolicyManager)getApplicationContext().getSystemService("device_policy");
mDPM.lockNow();
// You can also display overlay screen
return "Are you sure you want to disable the Device admin?";//OR whatever message you would like to display
}
}
As per documentation
Called when the user has asked to disable the administrator, as a result of receiving ACTION_DEVICE_ADMIN_DISABLE_REQUESTED, giving you a chance to present a warning message to them. The message is returned as the result; if null is returned (the default implementation), no message will be displayed.
Note:
If you are trying to display overlay screen, do note that disable popup will and deactivate screen will have high visibility precedence. Any attempts to do so won't help much. One work around is to lock screen first and then display overlay screen.

First addCommand() item in a Form fails when used with native theme

I have encountered a problem when using the the addCommand() method of the Form class along with the Native theme - other themes work fine. See the following example:
Form hi = new Form("Hi World");
hi.addComponent(new Label("Hi World"));
// with native theme - can't click on the first command in the list
hi.addCommand(new Command("Dummy1") {
public void actionPerformed(ActionEvent ev) {
Dialog.show("Dummy1 Clicked!", "You clicked the Dummy1", "OK", null);
}
});
hi.addCommand(new Command("Dummy2") {
public void actionPerformed(ActionEvent ev) {
Dialog.show("Dummy2 Clicked!", "You clicked the Dummy2", "OK", null);
}
});
hi.show();
When I create an application using the code above, a click on the second command ("Dummy2") produces the expected Dialog, but a click on the first command ("Dummy1") does nothing.
This only happens when using the Native theme. If I switch to Flat Blue, then clicking on either command produces the expected Dialog.
This behavior happens both on the Simulator and on a real Android device (don't know about iOS).
Fyi, my toolchain is NetBeans IDE v8.2, Java 1.8.0_25, with the CodenameOne plugin v3.6.0.
Has anyone else seen this? Am I missing something? If so, is there a workaround?

If the element is very narrow and very close to the top the click might be misinterpreted as a click out of bounds or on the status bar area. You need to set the styling of the SideCommand to have a sensible default as this element is very application specific. Otherwise touches might be lost.

I tried styling the SideCommand but it didn't seem to help. What worked for me was to define a style for TitleArea and simply uncheck Derived for the Padding settings (I left them all set to 0px).
I have no idea why this works - I would have thought that the derived values would have been zero in any case.

Selenium Webdriver : Dismiss Chrome Alert

I want to select the check box Prevent this page from creating additional dialogs before selecting ok to close the alert
Currently i am using
Alert alert=driver.switchTo().alert();
//check the checkbox
alert.accept();
As an normal interactive user to check the check box i have to use a combination of <Tab> + <Space/Enter> keys. The <Tab> shifts the focus to the check-box and the <Space/Enter> checks the check-box.
Solutions Tried
I tried using Java sendKeys mechanisms ( Robot class, driver.sendKeys(), etc.), but an UnhandledAlertException is getting thrown.
I tried using alert.sendKeys which is different from driver.sendKeys() but it too failed
//check the checkbox
alert.sendKeys("\t");
alert.sendKeys("{TAB}");
alert.sendKeys("\uE004");
alert.sendKeys("\\U+0009");
alert.sendKeys(Integer.toString(KeyEvent.VK_TAB));
I am trying to avoid robot class as much as possible as i need to run the test in grid in which case robot class will not work.Any pointers on how to send keys to the alert window ?
Temporarily i could do it using a javascript window.alert = function() {}; by simply overriding the alert with an empty function just curious to know if it could be done with webdriver functions like alert.sendkeys or any other methods ??
Any help is greatly appreciated!!

I want to run the application in background of mobile without any GUI in mobile using J2ME?

I am developing the network application in which I want to run my J2ME MIDP application in background without any GUI so that is any way to construct the application is such manner.

try this
set your current Display to null. so there will not be any form or alert running on the screen. But however your code will be running in the background.
Display display = Display.getDisplay(this); // here 'this' points to Midlet
display.setCurrent(null);

it easy just have a code of line on any event for example in the click of button
Display.getDisplay (this).setCurrent (null);
and return back the control via
Display.getDisplay (this).setCurrent (mycanvas);

Yes this code works Good,
display = Display.getDisplay(this);
public void startApp()
{
display.setCurrent(form);
}
public void pauseApp()
{
}
public void hide()
{
Display.getDisplay (this).setCurrent (null);
}
This is will work like, make a button can after clicking it call hide Function, or you call this hide function in constructor so it will hide itself when app start, can you keep unHide statement in appStart() so if you Tab the program then it will unHide app again.
NOTE: you said you are working on Network app, but some mobile will turn off the Internet Connection, when the Mobile screen Turn Off. please check this. and If you found any solution It will be Good to share here.