OnJava8-Examples/references/Snake.java

// references/Snake.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Tests cloning to see if reference
// destinations are also cloned

public class Snake implements Cloneable {
  private Snake next;
  private char c;
  // Value of i == number of segments
  public Snake(int i, char x) {
    c = x;
    if(--i > 0)
      next = new Snake(i, (char)(x + 1));
  }
  public void increment() {
    c++;
    if(next != null)
      next.increment();
  }
  @Override
  public String toString() {
    String s = ":" + c;
    if(next != null)
      s += next.toString();
    return s;
  }
  @Override
  public Snake clone() {
    try {
      return (Snake)super.clone();
    } catch(CloneNotSupportedException e) {
      throw new RuntimeException(e);
    }
  }
  public static void main(String[] args) {
    Snake s = new Snake(5, 'a');
    System.out.println("s = " + s);
    Snake s2 = s.clone();
    System.out.println("s2 = " + s2);
    s.increment();
    System.out.println("after s.increment, s2 = " + s2);
  }
}
/* Output:
s = :a:b:c:d:e
s2 = :a:b:c:d:e
after s.increment, s2 = :a:c:d:e:f
*/