NEED HELP USING JAVA

I'm implementing a chess game and I need to create a time class that shows the time elapsed since the start of the game. The timer must restart whenever the game restarts. When a new game starts, the timer resets. The time must show the total time elapsed since the start of the game. I need to append the timer class to a label in an .fxml file. Can someone show me a simple program to get started? I'm using javafx. Is there a method or something that could make this simple?

Example:

Here's my code so far:

/* Track the starting game time and compare to real time*/ public class ClockTimer { ClockTimer timer; public ClockTimer getTimer() { return timer; } } 

Opponent 10:00 8 22422 7 6 5 4 3 2 1 2 e Player 10:00 Opponent 10:00 8 22422 7 6 5 4 3 2 1 2 e Player 10:00