I have three fields namely

1. Number1
2. Number2
3. Time

I am trying to write a function in java that returns a unique hash value (long needs to be the return type of hash) for the above fields. This hash would then be used to store database rows corresponding to the above mentioned fields in a HashSet. I am new to writing a hash code function, can someone please review what I have. Any help would be appreciated.

public class HashCode {

private long Number1;
private long Number2;
String Time;

public HashCode(long Number1, long Number2, String Time){
    this.Number1 = Number1;
    this.Number2 = Number2;
    this.Time = Time;
}

public long getHashCode() {
    long hash = 3;
    hash = 47 * hash + (long) (this.Number1 ^ (this.Number1 >>> 32));
    hash = 47 * hash + (long) (this.Number2 ^ (this.Number2 >>> 32));
    hash = 47 * hash + (this.Time != null ? this.Time.hashCode() : 0);
    return hash;
}

}