Android Open Source - interdroid-swan Parseable Enum

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Copyright (c) 2008-2011 Vrije Universiteit, The Netherlands All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the follo...

Java Source Code

package interdroid.swan.swansong;
/*  w  w w .  ja  v a 2 s .  co  m*/
/**
 * This class is designed to make enumerations safe to persist more easily
 * while still allowing us to easily switch on enumerations and
 * also ensures that we can get a string version and return from a string
 * version of the enumeration for representation in expressions where the
 * string doesn't have to match the name of the enumeration value.
 *
 * Enums which implement this should implement static parse and convert methods
 * which returns the enum from the value for convenience. Unfortunately
 * there is now way for interfaces to force a static method and
 * all enumerations extend a single class. This is just a broken part
 * of java enumerations. Fortunately this method is easy to write:
  <code>
  public static E parse(String value) {
    return E.&gt;VALUE&lt;.parseString(value);
  }
  public static E convert(int value) {
    return E.&gt;VALUE&lt;.convertInt(value);
  }
  </code>
 *
 * This encourages the avoidance of using ordinal() to convert an enum
 * to an integer value since they can lead to problems if the enumeration
 * adds valid values at a later date.
 *
 * @author roelof &lt;rkemp@cs.vu.nl&gt;
 * @author nick &lt;palmer@cs.vu.nl&gt;
 *
 * @param <E>
 */
public interface ParseableEnum<E extends Enum<E>> extends Parseable<E> {

  /**
   * Converts this enum to an int value.
   * @return this enum as a safe to persist integer.
   */
  int convert();

  /**
   * Converts an int value back to the enum.
   * @param val the value to convert
   * @return the matching enumeration
   */
  E convertInt(int val);

  /* Highly recommended to include these static method.
  public static E parse(String val) {
    return VALUE.parseString(val);
  }

  public static E convert(String val) {
    return VALUE.convertInt(val);
  }
  */

  /**
   * @return a parseable version of the enum value.
   */
  @Override
  String toParseString();
}

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