001 package com.croftsoft.core.util.state;
002
003 /*********************************************************************
004 *
005 * Static methods to support concrete implementations of the State
006 * interface.
007 *
008 * <P>
009 *
010 * Reference:<BR>
011 * Mark Roulo,
012 * <A HREF="http://www.javaworld.com/javaworld/jw-01-1999/jw-01-object.html">
013 * "How to avoid traps and correctly override methods
014 * from java.lang.Object"</A>, January 1999, JavaWorld.
015 *
016 * <P>
017 *
018 * @author
019 * <a href="https://www.croftsoft.com/">David Wallace Croft</a>
020 * @version
021 * 1999-02-06
022 *********************************************************************/
023
024 public class StateLib
025 //////////////////////////////////////////////////////////////////////
026 //////////////////////////////////////////////////////////////////////
027 {
028
029 private StateLib ( ) { }
030
031 /*********************************************************************
032 * Returns true if the classes and State keys are equal.
033 *
034 * State implementation usage:
035 * <PRE>
036 * public boolean equals ( Object other )
037 * {
038 * return StateLib.equals ( this, other );
039 * }
040 * </PRE>
041 *********************************************************************/
042 public static boolean equals ( State state, Object other )
043 //////////////////////////////////////////////////////////////////////
044 {
045 if ( state == null )
046 {
047 throw new IllegalArgumentException ( "null state" );
048 }
049
050 if ( ( other == null )
051 || !other.getClass ( ).equals ( state.getClass ( ) ) )
052 {
053 return false;
054 }
055
056 return state.getKey ( ).equals ( ( ( State ) other ).getKey ( ) );
057 }
058
059 /*********************************************************************
060 * Returns the hash code of the State key.
061 *
062 * <PRE>
063 * return state.getKey ( ).hashCode ( );
064 * </PRE>
065 *
066 * State implementation usage:
067 * <PRE>
068 * public int hashCode ( )
069 * {
070 * return StateLib.hashCode ( this );
071 * }
072 * </PRE>
073 *********************************************************************/
074 public static int hashCode ( State state )
075 //////////////////////////////////////////////////////////////////////
076 {
077 return state.getKey ( ).hashCode ( );
078 }
079
080 //////////////////////////////////////////////////////////////////////
081 //////////////////////////////////////////////////////////////////////
082 }