enum type with its own method : enum « Data Type « Java Tutorial

public class SizeIterator {

  public static void main(String[] args) {
    Size[] sizes = Size.values();
    for (Size s : sizes) {
      System.out.println(s);
    }
  }
}

enum Size implements Countable {
  S, M, L, XL, XXL, XXXL;
  @Deprecated
  public Size increase() {
    Size sizes[] = this.values();
    int pos = this.ordinal();
    if (pos < sizes.length - 1)
      pos++;
    return sizes[pos];
  }
}

interface Countable {
  public Size increase();
}

2.43.enum
	2.43.1.	Enumeration Fundamentals
	2.43.2.	How to define an enumeration
	2.43.3.	Enums in a Class
	2.43.4.	equals and = operator for enum data type
	2.43.5.	Comparing Enumeration Values
	2.43.6.	Two enumeration constants can be compared for equality by using the == relational operator
	2.43.7.	uses an enum, rather than interface variables, to represent the answers.
	2.43.8.	enum type with its own method
	2.43.9.	Enum type field
	2.43.10.	enum with switch