Competitive access to running variable in DefaultClock #20
Description
The "running" variable of DefaultClock is changed by the main thread through "start()", "pause()" or "resume()" and read by the timer thread through "run()". In the "run()" method, the timer thread caches the variable state and even if the main thread do change its value, the timer thread can keep the wrong one in its cache.
To avoid this problem just add "volatile" attribute to the "running" variable :
public class DefaultClock extends Clock implements Runnable{
volatile boolean running;