/* EnumSyntax.java --
Copyright (C) 2003, 2005 Free Software Foundation, Inc.
This file is part of GNU Classpath.
GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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02110-1301 USA.
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
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permission to link this library with independent modules to produce an
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package javax.print.attribute;
import java.io.InvalidObjectException;
import java.io.ObjectStreamException;
import java.io.Serializable;
/**
* <code>EnumSyntax</code> is the abstract base class of all enumeration
* classes in the Java Print Service API.
* <p>
* Every enumeration class which extends from EnumSyntax provides several
* enumeration objects as singletons of its class.
* </p>
* <p>
* Notes for implementing subclasses:
* <ul>
* <li>
* The values of all enumeration singelton instances have to be in a
* sequence which may start at any value. See: {@link #getOffset()}
* </li>
* <li>
* Subclasses have to override {@link #getEnumValueTable()} and should
* override {@link #getStringTable()} for correct serialization.
* </li>
* </ul>
* </p>
* Example:
* <pre>
* public class PrinterState extends EnumSyntax
* {
* public static final PrinterState IDLE = new PrinterState(1);
* public static final PrinterState PROCESSING = new PrinterState(2);
* public static final PrinterState STOPPED = new PrinterState(3);
*
* protected PrinterState(int value)
* {
* super(value);
* }
*
* // Overridden because values start not at zero !
* protected int getOffset()
* {
* return 1;
* }
*
* private static final String[] stringTable = { "idle", "processing",
* "stopped" };
*
* protected String[] getStringTable()
* {
* return stringTable;
* }
*
* private static final PrinterState[] enumValueTable = { IDLE,
* PROCESSING, STOPPED};
*
* protected EnumSyntax[] getEnumValueTable()
* {
* return enumValueTable;
* }
* }
* </pre>
*
* @author Michael Koch (konqueror@gmx.de)
* @author Wolfgang Baer (WBaer@gmx.de)
*/
public abstract class EnumSyntax implements Cloneable, Serializable
{
private static final long serialVersionUID = -2739521845085831642L;
private int value;
/**
* Creates a <code>EnumSyntax</code> object.
*
* @param value the value to set.
*/
protected EnumSyntax(int value)
{
this.value = value;
}
/**
* Returns the value of this enumeration object.
*
* @return The value.
*/
public int getValue()
{
return value;
}
/**
* Clones this object.
*
* @return A clone of this object.
*/
public Object clone()
{
try
{
return super.clone();
}
catch (CloneNotSupportedException e)
{
// Cannot happen as we implement java.lang.Cloneable.
return null;
}
}
/**
* Returns the hashcode for this object.
* The hashcode is the value of this enumeration object.
*
* @return The hashcode.
*/
public int hashCode()
{
return value;
}
/**
* Returns the string representation for this object.
* The string value from <code>getStringTable()</code> method is returned
* if subclasses override this method. Otherwise the value of this object
* as a string is returned.
*
* @return The string representation.
*/
public String toString()
{
int index = value - getOffset();
String[] table = getStringTable();
if (table != null
&& index >= 0
&& index < table.length)
return table[index];
return "" + value;
}
/**
* Returns a table with the enumeration values represented as strings
* for this object.
*
* The default implementation just returns null. Subclasses should
* override this method.
*
* @return The enumeration values as strings.
*/
protected String[] getStringTable()
{
return null;
}
/**
* Needed for singelton semantics during deserialisation.
*
* Subclasses must not override this class. Subclasses have to override
* <code>getEnumValueTable()</code> and should override
* <code>getStringTable()</code> for correct serialization.
*
* @return The Object at index <code>value - getOffset()</code>
* in getEnumValueTable.
* @throws ObjectStreamException if getEnumValueTable() returns null.
*/
protected Object readResolve() throws ObjectStreamException
{
EnumSyntax[] table = getEnumValueTable();
if (table == null)
throw new InvalidObjectException("Null enumeration value table "
+ "for class "
+ this.getClass().toString());
return table[value - getOffset()];
}
/**
* Returns a table with the enumeration values for this object.
*
* The default implementation just returns null. Subclasses have to
* to override this method for serialization.
*
* @return The enumeration values.
*/
protected EnumSyntax[] getEnumValueTable()
{
return null;
}
/**
* Returns the lowest used value by the enumerations of this class.
*
* The default implementation returns 0. This is enough if enumerations
* start with a zero value. Otherwise subclasses need to override this
* method for serialization and return the lowest value they use.
* .
* @return The lowest used value used.
*/
protected int getOffset()
{
return 0;
}
}