public void setMemberType(String memberType)
    {
        switch(memberType)
        {
            case "junior": this.memberType = MemberType.junior; break;
            case "senior": this.memberType = MemberType.senior; break;
            case "recreational": this.memberType = MemberType.recreational; break;
            case "retiree": this.memberType = MemberType.retiree; break;
            default: throw new IllegalArgumentException("ERROR - invalid member type");
        } 
    }