School class with hashCode() and equals() From a challenge at http://beust.com/weblog/2013/02/13/coding-challenge-light-edition/

School.java

/*
 * A few assumptions:
 *  * School is immutable (otherwise, implementing hashCode/equals doesn't really make sense)
 *  * The problem is incompletely specified, with respect to how to handle missing values:
 *    * What do you do when both name and nickname are null?
 *    * What if one School has a name + nickname and the other has just a name, but the names match?
 *    My decision (and I think this is reasonable) is: Both must match. If a value is null in one,
 *    it must be null in the other to be considered equal
 */
class School {
  private String name;
  private String nickname;

  private boolean stringsEqual(String one, String two) {
    if (one == null) {
      if (two == null) {
        return true;
      } else {
        return false;
      }
    } else {
      return one.equals(two);
  }

  @Override
  public boolean equals(Object o) {
    if (o == null || !(o instanceof School)) {
      return false;
    }
    School os = (School)o;
    return stringsEqual(this.name, os.name) && stringsEqual(this.nickname, os.nickname);
  }

  @Override
  public int hashCode() {
    if (name != null) {
      if (nickname != null) {
        return (name + nickname).hashCode();
      } else {
        return name.hashCode();
      }
    } else {
      if (nickname != null) {
        return nickname.hashCode();
      } else {
        return 0;
      }
    }
  }
}