2 be atomic or 2 not be atomic

//class Derp would be initiated in another class and on a sperate thread and getTime()
//would be periodically accesed to reset the time value back to 0
public class Derp{
    private AtomicLong time = new AtomicLong(0);

    //somewhere here time is modified

    public AtomicLong getTime(){
        return time;
    }
}

//Could I use the following to bypass the need for the atomic part
public class Derp {
    private long time = 0;

    //somewhere here time is modified

    public void resetTime() {
        time - 0;
    }
}
//only resetTime would be called the exact value of time would never be needed
//Since the Derp class would be on a seperate thread then the class resetting the
//time would I run into any problems?