/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
***************************************************************************************
*/
/*
* Credit: Apache Commons Collections
*/
package com.espertech.esper.collection.apachecommons;
import java.util.Iterator;
/**
* Defines an iterator that operates over a <code>Map</code>.
* <p>
* This iterator is a special version designed for maps. It can be more
* efficient to use this rather than an entry set iterator where the option
* is available, and it is certainly more convenient.
* <p>
* A map that provides this interface may not hold the data internally using
* Map Entry objects, thus this interface can avoid lots of object creation.
* <p>
* In use, this iterator iterates through the keys in the map. After each call
* to <code>next()</code>, the <code>getValue()</code> method provides direct
* access to the value. The value can also be set using <code>setValue()</code>.
* <pre>
* MapIterator it = map.mapIterator();
* while (it.hasNext()) {
* Object key = it.next();
* Object value = it.getValue();
* it.setValue(newValue);
* }
* </pre>
*
* @author Stephen Colebourne
* @version $Revision$ $Date$
* @since Commons Collections 3.0
*/
public interface MapIterator extends Iterator {
/**
* Checks to see if there are more entries still to be iterated.
*
* @return <code>true</code> if the iterator has more elements
*/
boolean hasNext();
/**
* Gets the next <em>key</em> from the <code>Map</code>.
*
* @return the next key in the iteration
* @throws java.util.NoSuchElementException if the iteration is finished
*/
Object next();
//-----------------------------------------------------------------------
/**
* 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
*/
Object 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
*/
Object getValue();
//-----------------------------------------------------------------------
/**
* Removes the last returned key from the underlying <code>Map</code> (optional operation).
* <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
* or if <code>remove()</code> has already been called
* since the last call to <code>next()</code>
*/
void remove();
/**
* Sets the value associated with the current key (optional operation).
*
* @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
* or if <code>remove()</code> has been called since the
* last call to <code>next()</code>
*/
Object setValue(Object value);
}