Click Event handler - gwt

Question

when i click on a button the click event handler executes a code . If by mistake(if browser hangs) i click on the button twice the code gets executed twice.i dont want that to happen.
Any suggestions to stop that?
i suppose i should use a schedular or timer but i am not sure
below is the code:
public void onSendButtonClicked() {
disableButtons();
eventBus.fireEvent(new SendEmcsDeclarationEvent(getDeclaration(), getMsgType()));
}

Answer 1

You can - as Abdullah mentioned - disable/enable every widget in GWT with
widget.setEnable(false)
and
widget.setEnable(true).
If you want to lock the whole screen, create a modal popup, show it, after the button is pressed and hide it, after the code has finished.
public void onSendButtonClicked() {
myProgessBar.show();
eventBus.fireEvent(new SendEmcsDeclarationEvent(getDeclaration(), getMsgType()));
myProgressBar.hide();
}
If you are using a async call, you have to hide the progessbar in the callbacks. In this case the finally command might be executed before the callback is executed. In your case it might be a good idea to create a ShowProgressBarEvent and HideProgressbarEvent, so that you can use the progressbar in your whole application.
If your are using a widget library f.e.: GXT, you will find a ProgressBar ready to use.
Hope that helps.

Answer 2

The best way I can think of is to enable/disable the button itself so as to make sure that the code in handler is not called again until before the previous call finishes up.
public void onSendButtonClicked()
{
try
{
disableButtons();
eventBus.fireEvent(new SendEmcsDeclarationEvent(getDeclaration(), getMsgType()));
}
catch (Exception ex)
{
throw ex;
}
finally
{
enableButtons();
}
}

Answer 3

When I create a button, I always also add an animating gif (ajaxloader).
When the button is clicked I make the button invisble, the ajaxloader visible.
When the action is done, I make the ajaxloader invisible, and the button visible.
This way the user has some visual feedback that something is happening (what you don't get when disabling the button), and not the entire application gets blocked (as a modal does) which is one of the plus points using ajax.