/*
* Copyright 2001-2004 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.iterators;
import java.util.Iterator;
import java.util.Map;
import org.apache.commons.collections.MapIterator;
import org.apache.commons.collections.ResettableIterator;
/**
* Implements a <code>MapIterator</code> using a Map entrySet.
* Reverse iteration is not supported.
* <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 class EntrySetMapIterator implements MapIterator, ResettableIterator {
private final Map map;
private Iterator iterator;
private Map.Entry last;
private boolean canRemove = false;
/**
* Constructor.
*
* @param map the map to iterate over
*/
public EntrySetMapIterator(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 java.util.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);
}
//-----------------------------------------------------------------------
/**
* 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[]";
}
}
}