/*
* Copyright 2003-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.collections;
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>
*
* @since Commons Collections 3.0
* @version $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
*
* @author Stephen Colebourne
*/
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
* @throws IllegalStateException 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
* @throws IllegalStateException if <code>remove()</code> has been called since the
* last call to <code>next()</code>
*/
Object setValue(Object value);
}