digitalclock

Vaadin Digital Clock

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The client-side widget, after instantiation, maintains 2 GWT timer objects. One timer is scheduled to fetch the server time every 5 minutes from the web-app server. The other timer is scheduled to execute every second to keep the client-side clock ticking.

The information (or STATE) that is transferred between the client-side widget & the server-side component is a long variable called "time" which holds the current server time in milliseconds.

GWT RPC is used in the background to invoke the piece of code in the server-side component that actually calculates the current server time.

Sample code

public class DigitalclockUI extends UI {

	@Override
	protected void init(VaadinRequest request) {
		final VerticalLayout layout = new VerticalLayout();
		layout.setMargin(true);
		setContent(layout);

		layout.addComponent(new DigitalClock());
	}

}

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