public Challenge(String createdBy, String opponent,
		int creatorColor, int min_rating, int max_rating, Date createdOn) {
	this.createdBy = createdBy;
	this.opponent = opponent;
	this.creatorColor = creatorColor==1?"white":"black";
	this.min_rating = Math.min(min_rating,max_rating);
	this.max_rating = Math.max(min_rating,max_rating);
	this.createdOn = createdOn;
}