A performant way of testing enum membership and parsing an enum from text.

gistfile1.java

public enum FuBar
{
  ONE("one"),

  TWO("two");

  private static final String PATT;
  private static final Map<String,FuBar> MAP;

  static
  {
    MAP = new HashMap<String,FuBar>();

    StringBuilder sb = new StringBuilder("(?i)");
    for (FuBar e : FuBar.values())
    {
      if (sb.length() > 4)
      {
        sb.append("|");
      }
      
      sb.append(e);

      MAP.put(e.toString().toUpperCase(), e);
    }
  }

  private final String value;

  private FuBar(String value)
  {
    this.value = value;
  }

  public boolean isFuBar(String text)
  {
    if (text == null)
    {
      throw new IllegalArgumentException("text is null");
    }

    return text.matches(PATT);
  }

  public FuBar parse(String text)
  {
    if (!isFuBar(text))
    {
      return null;
    }
    
    return MAP[text.toUpperCase()];
  }

  @Override
  public String toString()
  {
    return this.value;
  }
}