blog_compare_to_java_style.groovy

    int compareTo(Person other) {
        if (other == null) {
            return 1;
        }

        int result = 0;
        if (this.age > other.age) {
            result = 1;
        }
        else if (this.age < other.age) {
            result = -1;
        }
        if (result == 0) {
            if (this.lastName != null && other.lastName != null) {
                result = this.lastName.compareTo(other.lastName);
                if (result == 0) {
                    if (this.firstName != null && other.firstName != null) {
                        result = this.firstName.compareTo(other.firstName);
                    }
                    else {
                        result = this.firstName != null ? 1 : -1;
                    }
                }
            }
            else {
                result = this.lastName != null ? 1 : -1;
            }
        }
        return result;
    }