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Posted to dev@commons.apache.org by sc...@apache.org on 2003/11/03 00:40:53 UTC
cvs commit: jakarta-commons/collections/src/java/org/apache/commons/collections/iterators DefaultMapIterator.java
scolebourne 2003/11/02 15:40:53
Added: collections/src/java/org/apache/commons/collections/iterators
DefaultMapIterator.java
Log:
Add a default MapIterator implementation that wraps a Map entrySet
Revision Changes Path
1.1 jakarta-commons/collections/src/java/org/apache/commons/collections/iterators/DefaultMapIterator.java
Index: DefaultMapIterator.java
===================================================================
/*
* $Header: /home/cvs/jakarta-commons/collections/src/java/org/apache/commons/collections/iterators/DefaultMapIterator.java,v 1.1 2003/11/02 23:40:53 scolebourne 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
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*
* 2. Redistributions in binary form must reproduce the above copyright
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* distribution.
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* any, must include the following acknowledgement:
* "This product includes software developed by the
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* Alternately, this acknowledgement may appear in the software itself,
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* ====================================================================
*
* This software consists of voluntary contributions made by many
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*/
package org.apache.commons.collections.iterators;
import java.util.Iterator;
import java.util.Map;
import org.apache.commons.collections.pairs.TiedMapEntry;
/**
* Implements a <code>MapIterator</code> using a Map entrySet.
* <pre>
* MapIterator it = map.mapIterator();
* while (it.hasNext()) {
* Object key = it.next();
* Object value = it.getValue();
* it.setValue(newValue);
* }
* </pre>
*
* @since Commons Collections 3.0
* @version $Revision: 1.1 $ $Date: 2003/11/02 23:40:53 $
*
* @author Stephen Colebourne
*/
public class DefaultMapIterator implements ResetableMapIterator {
private final Map map;
private Iterator iterator;
private Map.Entry last;
private boolean canRemove = false;
/**
* Constructor.
*
* @param map the map to iterate over
*/
public DefaultMapIterator(Map map) {
super();
this.map = map;
this.iterator = map.entrySet().iterator();
}
//-----------------------------------------------------------------------
/**
* Checks to see if there are more entries still to be iterated.
*
* @return <code>true</code> if the iterator has more elements
*/
public boolean hasNext() {
return iterator.hasNext();
}
/**
* Gets the next <em>key</em> from the <code>Map</code>.
*
* @return the next key in the iteration
* @throws NoSuchElementException if the iteration is finished
*/
public Object next() {
last = (Map.Entry) iterator.next();
canRemove = true;
return last.getKey();
}
/**
* Removes the last returned key from the underlying <code>Map</code>.
* <p>
* This method can be called once per call to <code>next()</code>.
*
* @throws UnsupportedOperationException if remove is not supported by the map
* @throws IllegalStateException if <code>next()</code> has not yet been called
* @throws IllegalStateException if <code>remove()</code> has already been called
* since the last call to <code>next()</code>
*/
public void remove() {
if (canRemove == false) {
throw new IllegalStateException("Iterator remove() can only be called once after next()");
}
iterator.remove();
last = null;
canRemove = false;
}
//-----------------------------------------------------------------------
/**
* Gets the current key, which is the key returned by the last call
* to <code>next()</code>.
*
* @return the current key
* @throws IllegalStateException if <code>next()</code> has not yet been called
*/
public Object getKey() {
if (last == null) {
throw new IllegalStateException("Iterator getKey() can only be called after next() and before remove()");
}
return last.getKey();
}
/**
* Gets the current value, which is the value associated with the last key
* returned by <code>next()</code>.
*
* @return the current value
* @throws IllegalStateException if <code>next()</code> has not yet been called
*/
public Object getValue() {
if (last == null) {
throw new IllegalStateException("Iterator getValue() can only be called after next() and before remove()");
}
return last.getValue();
}
/**
* Sets the value associated with the current key.
*
* @param value the new value
* @return the previous value
* @throws UnsupportedOperationException if setValue is not supported by the map
* @throws IllegalStateException if <code>next()</code> has not yet been called
* @throws IllegalStateException if <code>remove()</code> has been called since the
* last call to <code>next()</code>
*/
public Object setValue(Object value) {
if (last == null) {
throw new IllegalStateException("Iterator setValue() can only be called after next() and before remove()");
}
return last.setValue(value);
}
//-----------------------------------------------------------------------
/**
* Gets the last returned key-value pair from the underlying <code>Map</code>
* as a Map Entry instance.
* <p>
* The returned entry will not change when <code>next</code> is called.
* Changes made to the entry via <code>setValue</code> will change the map.
* If you call setValue after next on the iterator, a ConcurrentModificationException
* may occur.
*
* @return the last return key-value pair as an independent Map Entry
* @throws IllegalStateException if <code>next()</code> has not yet been called
* @throws IllegalStateException if <code>remove()</code> has been called since the
* last call to <code>next()</code>
*/
public Map.Entry asMapEntry() {
return new TiedMapEntry(map, getKey());
}
/**
* Resets the state of the iterator.
*/
public void reset() {
iterator = map.entrySet().iterator();
last = null;
canRemove = false;
}
/**
* Gets the iterator as a String.
*
* @return a string version of the iterator
*/
public String toString() {
if (last == null) {
return "MapIterator[" + getKey() + "=" + getValue() + "]";
} else {
return "MapIterator[]";
}
}
}
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