/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.collections4.iterators;

import java.util.Iterator;
import java.util.Map;

import org.apache.commons.collections4.MapIterator;
import org.apache.commons.collections4.ResettableIterator;

Implements a MapIterator using a Map entrySet. Reverse iteration is not supported.
MapIterator it = map.mapIterator();
while (it.hasNext()) {
  Object key = it.next();
  Object value = it.getValue();
  it.setValue(newValue);
}
Since:3.0
/** * 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 3.0 */
public class EntrySetMapIterator<K, V> implements MapIterator<K, V>, ResettableIterator<K> { private final Map<K, V> map; private Iterator<Map.Entry<K, V>> iterator; private Map.Entry<K, V> last; private boolean canRemove = false;
Constructor.
Params:
  • map – the map to iterate over
/** * Constructor. * * @param map the map to iterate over */
public EntrySetMapIterator(final Map<K, V> map) { super(); this.map = map; this.iterator = map.entrySet().iterator(); } //-----------------------------------------------------------------------
Checks to see if there are more entries still to be iterated.
Returns:true if the iterator has more elements
/** * Checks to see if there are more entries still to be iterated. * * @return <code>true</code> if the iterator has more elements */
@Override public boolean hasNext() { return iterator.hasNext(); }
Gets the next key from the Map.
Throws:
Returns:the next key in the iteration
/** * 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 */
@Override public K next() { last = iterator.next(); canRemove = true; return last.getKey(); } //-----------------------------------------------------------------------
Removes the last returned key from the underlying Map.

This method can be called once per call to next().

Throws:
  • UnsupportedOperationException – if remove is not supported by the map
  • IllegalStateException – if next() has not yet been called
  • IllegalStateException – if remove() has already been called since the last call to next()
/** * 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> */
@Override 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 next().
Throws:
Returns:the current key
/** * 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 */
@Override public K 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 next().
Throws:
Returns:the current value
/** * 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 */
@Override public V 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.
Params:
  • value – the new value
Throws:
Returns:the previous value
/** * 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> */
@Override public V setValue(final V 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.
/** * Resets the state of the iterator. */
@Override public void reset() { iterator = map.entrySet().iterator(); last = null; canRemove = false; }
Gets the iterator as a String.
Returns:a string version of the iterator
/** * Gets the iterator as a String. * * @return a string version of the iterator */
@Override public String toString() { if (last != null) { return "MapIterator[" + getKey() + "=" + getValue() + "]"; } return "MapIterator[]"; } }