--- Stephen Colebourne <[EMAIL PROTECTED]> wrote: > I'm currently struggling to understand why I would need to use a > HistoricMapEntry (better name?). > It has a part in the undo events code you wrote I believe, but > outside that > where does it fit and what use is it? Use cases please :-) > > Stephen
The better half is throwing dirty looks at me (I'm supposed to be painting the house) - I'll get back to you on the use cases asap. > PS. I guess this came from the rich events package, which I would > like to see as an implementation of the observed code. Guilty as charged... unfortunately i've been away from my open-source desk for the last month (in fact moving home, and - gasp! - no connectivity for weeks on end) and hadn't been able to devote time to the notifying/observable work, but i certainly want to integrate the code, so I'll be looking into this next chance I get. Neil > ----- Original Message ----- > From: "Neil O'Toole" <[EMAIL PROTECTED]> > > > 'Record' confused me and made me think of databases. Is > > > KeyValueHistory a better name? > > > > Stephen, you're probably right. I had been bouncing back and forth > > between 'Record' and 'History'... the data structure does *record* > a > > kv-pair's *history*, but in fact only the most recent part (one > state > > transition 'record') of the history. > > > > However, one would expect that a "KeyValueHistory" class should be > able > > to store the entire history of a key (as well as just a single > value). > > I hadn't initially needed this capability for my own purposes, but > I > > now see the usefulness. So, > > > > #getPreviousValue : Object > > > > should probably be replaced with: > > > > #getAllValues : List > > > > What do we think? In terms of design, either the constructors would > get > > very messy to use, or we need to add factory methods to distinguish > > between: > > > > KeyValueHistory( Object key, Object value) > > KeyValueHistory( Object key, List values) > > > > Attached is an implementation that supports multiple previous > values, > > and provides static factory methods. Thoughts? > > > > - Neil > > > > > > > > > ---------------------------------------------------------------------------- > ---- > > > > /* > > * $Header: > x:/apps/cvsnt/cvs_repository/main/notifyingcollections/src/java/org/apache/c > ommons/collections/KeyValueRecord.java,v 1.2 2003/09/20 22:00:32 > otoolen Exp > $ > > * > ==================================================================== > > * > > * The Apache Software License, Version 1.1 > > * > > * Copyright (c) 2001-2003 The Apache Software Foundation. All > rights > > * reserved. > > * > > * Redistribution and use in source and binary forms, with or > without > > * modification, are permitted provided that the following > conditions > > * are met: > > * > > * 1. Redistributions of source code must retain the above > copyright > > * notice, this list of conditions and the following disclaimer. > > * > > * 2. Redistributions in binary form must reproduce the above > copyright > > * notice, this list of conditions and the following disclaimer > in > > * the documentation and/or other materials provided with the > > * distribution. > > * > > * 3. The end-user documentation included with the redistribution, > if > > * any, must include the following acknowledgment: > > * "This product includes software developed by the > > * Apache Software Foundation (http://www.apache.org/)." > > * Alternately, this acknowledgment may appear in the software > itself, > > * if and wherever such third-party acknowledgments normally > appear. > > * > > * 4. The names "The Jakarta Project", "Commons", and "Apache > Software > > * Foundation" must not be used to endorse or promote products > derived > > * from this software without prior written permission. For > written > > * permission, please contact [EMAIL PROTECTED] > > * > > * 5. Products derived from this software may not be called > "Apache" > > * nor may "Apache" appear in their names without prior written > > * permission of the Apache Software Foundation. > > * > > * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED > > * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED > WARRANTIES > > * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE > > * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR > > * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, > > * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT > > * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF > > * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED > AND > > * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT > LIABILITY, > > * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY > OUT > > * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY > OF > > * SUCH DAMAGE. > > * > ==================================================================== > > * > > * This software consists of voluntary contributions made by many > > * individuals on behalf of the Apache Software Foundation. For > more > > * information on the Apache Software Foundation, please see > > * <http://www.apache.org/>. > > * > > */ > > package org.apache.commons.collections; > > > > import java.util.ArrayList; > > import java.util.Collections; > > import java.util.List; > > import java.util.Map; > > > > /** > > * An immutable {key, value, previous-value} triplet. This class is > frequently used > > * in conjunction with <code>Map.Entry</code>. A constructor is > provided > to create > > * a <code>KeyValueRecord</code> from a <code>Map.Entry</code>, and > the > [EMAIL PROTECTED] #asMapEntry} > > * method can be used to view an object of this class as a > <code>Map.Entry</code>. > > * Note that it is not possible for <code>KeyValueRecord</code> to > implement the <code>Map.Entry</code> > > * interface as the <code>#equals</code> implementations are not > compatible. > > * > > * > > * > > * @author Neil O'Toole > > */ > > > > public class KeyValueHistory > > { > > > > /** > > * Create a new <code>KeyValueHistory</code> with supplied key and > value, > > * and no previous values. > > */ > > public static KeyValueHistory createFromKeyValue(final Object key, > final > Object value) > > { > > return new KeyValueHistory(key, Collections.singletonList(value)); > > } > > > > > > /** > > * Create a new <code>KeyValueHistory</code> with the specified key > and > values. > > * The supplied list must: > > * <ul> > > * <li>contain at least one value</li> > > * <li>contain the values in reverse-chronological order (i.e. most > > * recent value first)</li> > > * <li>be immutable</li> > > * </ul> > > * > > * @param values an immutable list of the values associated with > this key. > > * @throws IllegalArgumentException if <code>values</code> is > <code>null</code> or > > * is empty. <br />Note: If the value associated with the key is the > value > <code>null</code>, > > * then supply <code>Collections#singletonList( null )</code>. > > */ > > public static KeyValueHistory createFromKeyValueList(final Object > key, > final List values) > > { > > if (values == null || values.size() < 1) > > { > > throw new IllegalArgumentException("The supplied 'values' list must > contain at least one value."); > > } > > > > return new KeyValueHistory(key, values); > > } > > > > /** > > * Create a new <code>KeyValueHistory</code> with supplied key, > value > > * and previous value. > > */ > > public static KeyValueHistory createFromKeyValuePrevious(final > Object key, > final Object value, final Object previous) > > { > > final List values = new ArrayList(2); > > values.add(value); > > values.add(previous); > > > > return new KeyValueHistory(key, > Collections.unmodifiableList(values)); > > } > > /** > > * Create a new <code>KeyValueHistory</code> with key and value from > the > supplied > > * <code>Map.Entry</code> and no previous value. > > */ > > public static KeyValueHistory createFromMapEntry(final Map.Entry > entry) > > { > > return new KeyValueHistory(entry.getKey(), > Collections.singletonList(entry.getValue())); > > } > > > > private int hash = -1; // lazily calculated > > > > private final Object key; > > private final List values; > > > > > > > > > > /** > > * Create a new <code>KeyValueHistory</code> with the specified key > and > values. > > * The supplied list: > > * <ul> > > * <li>must contain at least one value</li> > > * <li>must contain the values in reverse-chronological order (i.e. > most > > * recent value first)</li> > > * <li>must be immutable</li> > > * > > * @param values an immutable List of the values associated with > this key. > > */ > > protected KeyValueHistory(final Object key, final List values) > > { > > this.key = key; > > this.values = values; > > } > > > > /** > > * Returns a [EMAIL PROTECTED] Map.Entry} view of the supplied > <code>KeyValueRecord</code>. The > > * returned entry is unmodifiable (<code>#setValue</code> throws an > [EMAIL PROTECTED] > UnsupportedOperationException}), > > * as the backing <code>KeyValueRecord</code> is itself immutable. > > * The returned entry correctly implements the > <code>#hashCode</code> and > > * <code>#equals</code> operations as per the <code>Map.Entry</code> > contract. > > */ > > > > public Map.Entry asMapEntry() > > { > > return new Map.Entry() > > { > > private int hash = -1; > > > > public boolean equals(Object o) > > { > > if (o instanceof Map.Entry == false) > > { > > return false; > > } > > > > if (o == this) > > { > > return true; > > } > > > > Map.Entry e = (Map.Entry) o; > > > > return ( > > KeyValueHistory.this.getKey() == null > > ? e.getKey() == null > > : KeyValueHistory.this.getKey().equals(e.getKey())) > > && (KeyValueHistory.this.getValue() == null > > ? e.getValue() == null > > : KeyValueHistory.this.getValue().equals(e.getValue())); > > } > > > > public Object getKey() > > { > > return KeyValueHistory.this.getKey(); > > } > > > > public Object getValue() > > { > > return KeyValueHistory.this.getValue(); > > } > > > > public int hashCode() > > { > > if (this.hash == -1) > > { > > this.hash = > > (KeyValueHistory.this.getKey() == null ? 0 : > KeyValueHistory.this.getKey().hashCode()) > > ^ (KeyValueHistory.this.getValue() == null ? 0 : > KeyValueHistory.this.getValue().hashCode()); > > } > > > > return this.hash; > > } > > > > public Object setValue(Object value) > > { > > throw new UnsupportedOperationException("This Map.Entry is > unmodifiable."); > > } > > > > public String toString() > > { > > return new StringBuffer() > > .append(KeyValueHistory.this.getKey()) > > .append('=') > > .append(KeyValueHistory.this.getValue()) > > .toString(); > > } > > }; > > > > } > > > > /** > > * Compares the specified object with this > <code>KeyValueRecord</code> for > equality. Returns > > * true if the given object is also a <code>KeyValueRecord</code> > and > > * the records' key, value, and previous value are equal. > > * > > * @param o object to be compared for equality with this > <code>KeyValueRecord</code>. > > * @return <code>true</code> if the specified object is equal to > this > > * record. > > */ > > public boolean equals(final Object o) > > { > > if (!(o instanceof KeyValueHistory)) > > { > > return false; > > } > > > > if (this == o) > > { > > return true; > > } > > > > final KeyValueHistory kvr = (KeyValueHistory) o; > > > > return (this.key == null ? kvr.key == null : > this.key.equals(kvr.key)) > > && this.values.equals(kvr.values); > > } > > > > /** > > * Returns the first value previously associated with this key, if > any. > Note that > > * <code>null</code> will be returned > > * if the previous value is <code>null</code> <i>or</i> if there are > no > previous values > > * Therefore [EMAIL PROTECTED] #hasPreviousValues()} should be used to test if > there > is a previous value. > > * > > * @return the previous value (which may be <code>null</code>) > > * associated with this record's key, or <code>null</code> if there > is no > > * previous value. > > */ > > /* > > public Object getPreviousValue() > > { > > return (this.values.size() < 2) ? null : this.values.get(1); > > }*/ > > > > /* > > public List getAllPreviousValues() > > { > > return this.values.subList(1, values.size() -1); > > } > > */ > > > > /** > > * Return all values associated with this key, in reverse > chronological > > * order. The most recent (current) value is at index zero, the > previous > value is > > * at index one, the value previous to that at index two, etc.. If > there > are no > > * previous values associated with this key, then list will contain > only > one element (the current value). > > * The returned list is immutable. > > * > > * @return an immutable list of the values associated with this key, > the > list having a minimum size of one. > > */ > > public List getAllValues() > > { > > return this.values; > > } > > > > /** > > * Returns the key associated with this record. > > */ > > public Object getKey() > > { > > return this.key; > > } > > > > /** > > * Returns the current (or most recent) value associated with this > record's > key. > > * > > * @return the value (which may be <code>null</code>) > > * associated with this record's key > > */ > > public Object getValue() > > { > > return this.values.get(0); > > } > > > > public int hashCode() > > { > > if (this.hash == -1) > > { > > this.hash = > > (this.key == null ? 0 : this.key.hashCode()) > > ^ this.values.hashCode(); > > } > > > > return this.hash; > > } > > > > /** > > * Returns true if this record's key > > * was associated with a value previous to being > > * associated with its current value. > > * > > * @return <code>true</code> if this key previously had a value > associated > > * with it, <code>false</code> otherwise. > > * @see #getPreviousValue() > > */ > > public boolean hasPreviousValues() > > { > > return this.values.size() > 1; > > } > > > > /** > > * Returns a string representation of this > <code>KeyValueHistory</code>. > > * > > */ > > public String toString() > > { > > final StringBuffer sb = new > StringBuffer().append(this.key).append('=').append(this.values); > > > > return sb.toString(); > > } > > > > } > > > > > ---------------------------------------------------------------------------- > ---- > > > > /* > > * $Header: > x:/apps/cvsnt/cvs_repository/main/notifyingcollections/src/test/org/apache/c > ommons/collections/TestKeyValueHistory.java,v 1.1 2003/09/20 22:00:46 > otoolen Exp $ > > * > ==================================================================== > > * > > * The Apache Software License, Version 1.1 > > * > > * Copyright (c) 2001-2003 The Apache Software Foundation. All > rights > > * reserved. > > * > > * Redistribution and use in source and binary forms, with or > without > > * modification, are permitted provided that the following > conditions > > * are met: > > * > > * 1. Redistributions of source code must retain the above > copyright > > * notice, this list of conditions and the following disclaimer. > > * > > * 2. Redistributions in binary form must reproduce the above > copyright > > * notice, this list of conditions and the following disclaimer > in > > * the documentation and/or other materials provided with the > > * distribution. > > * > > * 3. The end-user documentation included with the redistribution, > if > > * any, must include the following acknowledgment: > > * "This product includes software developed by the > > * Apache Software Foundation (http://www.apache.org/)." > > * Alternately, this acknowledgment may appear in the software > itself, > > * if and wherever such third-party acknowledgments normally > appear. > > * > > * 4. The names "The Jakarta Project", "Commons", and "Apache > Software > > * Foundation" must not be used to endorse or promote products > derived > > * from this software without prior written permission. For > written > > * permission, please contact [EMAIL PROTECTED] > > * > > * 5. Products derived from this software may not be called > "Apache" > > * nor may "Apache" appear in their names without prior written > > * permission of the Apache Software Foundation. > > * > > * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED > > * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED > WARRANTIES > > * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE > > * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR > > * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, > > * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT > > * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF > > * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED > AND > > * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT > LIABILITY, > > * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY > OUT > > * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY > OF > > * SUCH DAMAGE. > > * > ==================================================================== > > * > > * This software consists of voluntary contributions made by many > > * individuals on behalf of the Apache Software Foundation. For > more > > * information on the Apache Software Foundation, please see > > * <http://www.apache.org/>. > > * > > */ > > package org.apache.commons.collections; > > > > import java.util.HashMap; > > import java.util.Map; > > > > import junit.framework.TestCase; > > > > > > /** > > * > > * @author Neil O'Toole > > */ > > public class TestKeyValueHistory extends TestCase > > { > > private final String key = "key"; > > private final String value = "value"; > > private final String previous = "previous"; > > > > public TestKeyValueHistory(String testName) > > { > > super(testName); > > > > } > > > > public static void main(String[] args) > > { > > junit.textui.TestRunner.run(TestKeyValueHistory.class); > > } > > > > public void testKeyValueHistory() > > { > > > > // KVR with no previous value > > KeyValueHistory kvr = KeyValueHistory.createFromKeyValue(key, > value); > > > > assertTrue( > > kvr.getKey() == key > > && kvr.getValue() == value > > && kvr.hasPreviousValues() == false); > > > > assertTrue(kvr.equals(kvr)); > > assertTrue(kvr.toString().equals("key=[value]")); > > > > // KVR with a previous value > > KeyValueHistory kvr2 = > KeyValueHistory.createFromKeyValuePrevious(key, > value, previous); > > > > assertTrue( > > kvr2.getKey() == key > > && kvr2.getValue() == value > > && kvr2.hasPreviousValues() == true > > && kvr2.getAllValues().get(1) == previous); > > > > assertTrue(kvr2.equals(kvr2)); > > assertTrue(kvr2.toString().equals("key=[value, previous]")); > > > > assertFalse(kvr.equals(kvr2)); > > assertFalse(kvr.hashCode() == kvr2.hashCode()); > > > > // test that a previous value of 'null' is treated differently to > no > previous value > > KeyValueHistory kvr3 = > KeyValueHistory.createFromKeyValuePrevious(key, > value, null); > > assertTrue(kvr3.equals(kvr3)); > > assertTrue(kvr3.toString().equals("key=[value, null]")); > > assertFalse(kvr3.equals(kvr)); > > assertFalse(kvr3.equals(kvr2)); > > > > assertFalse(kvr3.hashCode() == kvr2.hashCode()); > > assertFalse(kvr3.hashCode() == kvr.hashCode()); > > > > // test the Map.Entry handling > > Map map = new HashMap(); > > map.put(key, value); > > > > Map.Entry entry = (Map.Entry) map.entrySet().iterator().next(); > > > > KeyValueHistory kvr4 = KeyValueHistory.createFromMapEntry(entry); > > > > assertTrue( > > kvr4.getKey() == key > > && kvr4.getValue() == value > > && kvr4.hasPreviousValues() == false); > > > > assertTrue(kvr4.equals(kvr4)); > > assertTrue(kvr4.equals(kvr)); > > assertTrue(kvr4.toString().equals("key=[value]")); > > > > assertFalse("Map.Entry and KeyValueHistory are never equal", > kvr4.equals(entry)); > > > > Map.Entry entry2 = kvr4.asMapEntry(); > > > > assertTrue(entry.equals(entry2)); > > assertTrue(entry.hashCode() == entry2.hashCode()); > > > > } > > > > } > > > > > > > ---------------------------------------------------------------------------- > ---- > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: > [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
