Implements an java.util.Iterator over any array
/*
* 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.
*/
import java.lang.reflect.Array;
import java.util.NoSuchElementException;
/**
* Implements an {@link java.util.Iterator Iterator} over any array.
* <p>
* The array can be either an array of object or of primitives. If you know
* that you have an object array, the
* {@link org.apache.commons.collections.iterators.ObjectArrayIterator ObjectArrayIterator}
* class is a better choice, as it will perform better.
* <p>
* The iterator implements a {@link #reset} method, allowing the reset of
* the iterator back to the start if required.
*
* @since Commons Collections 1.0
* @version $Revision$ $Date$
*
* @author James Strachan
* @author Mauricio S. Moura
* @author Michael A. Smith
* @author Neil O'Toole
* @author Stephen Colebourne
*/
public class ArrayIterator implements java.util.Iterator {
/** The array to iterate over */
protected Object array;
/** The end index to loop to */
protected int endIndex = 0;
/** The current iterator index */
protected int index = 0;
/**
* Constructs an ArrayIterator that will iterate over the values in the
* specified array.
*
* @param array the array to iterate over.
* @throws IllegalArgumentException if <code>array</code> is not an array.
* @throws NullPointerException if <code>array</code> is <code>null</code>
*/
public ArrayIterator(final Object array) {
setArray(array);
}
/**
* Checks whether the index is valid or not.
*
* @param bound the index to check
* @param type the index type (for error messages)
* @throws IndexOutOfBoundsException if the index is invalid
*/
protected void checkBound(final int bound, final String type ) {
if (bound > this.endIndex) {
throw new ArrayIndexOutOfBoundsException(
"Attempt to make an ArrayIterator that " + type +
"s beyond the end of the array. "
);
}
if (bound < 0) {
throw new ArrayIndexOutOfBoundsException(
"Attempt to make an ArrayIterator that " + type +
"s before the start of the array. "
);
}
}
// Iterator interface
//-----------------------------------------------------------------------
/**
* Returns true if there are more elements to return from the array.
*
* @return true if there is a next element to return
*/
public boolean hasNext() {
return (index < endIndex);
}
/**
* Returns the next element in the array.
*
* @return the next element in the array
* @throws NoSuchElementException if all the elements in the array
* have already been returned
*/
public Object next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
return Array.get(array, index++);
}
/**
* Throws {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException always
*/
public void remove() {
throw new UnsupportedOperationException("remove() method is not supported");
}
// Properties
//-----------------------------------------------------------------------
/**
* Gets the array that this iterator is iterating over.
*
* @return the array this iterator iterates over, or <code>null</code> if
* the no-arg constructor was used and {@link #setArray(Object)} has never
* been called with a valid array.
*/
public Object getArray() {
return array;
}
/**
* Sets the array that the ArrayIterator should iterate over.
* <p>
* If an array has previously been set (using the single-arg constructor
* or this method) then that array is discarded in favour of this one.
* Iteration is restarted at the start of the new array.
* Although this can be used to reset iteration, the {@link #clear()} method
* is a more effective choice.
*
* @param array the array that the iterator should iterate over.
* @throws IllegalArgumentException if <code>array</code> is not an array.
* @throws NullPointerException if <code>array</code> is <code>null</code>
*/
private void setArray(final Object array) {
// Array.getLength throws IllegalArgumentException if the object is not
// an array or NullPointerException if the object is null. This call
// is made before saving the array and resetting the index so that the
// array iterator remains in a consistent state if the argument is not
// an array or is null.
this.endIndex = Array.getLength(array);
this.array = array;
this.index = 0;
}
}
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