--- /dev/null 2014-01-14 17:58:07.923182598 +0400 +++ new/src/share/demo/default-methods/ArrayIterator.java 2014-01-15 17:13:32.195705379 +0400 @@ -0,0 +1,125 @@ +/* + * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * - Neither the name of Oracle nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS + * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +import java.util.Iterator; +import java.util.NoSuchElementException; + +/** + * The code sample illustrates the usage of default methods in the JDK 8. Most + * implementations of Iterator don’t provide a useful remove() method, however, + * they still have to implement this method to throw + * an UnsupportedOperationException. With the default method, the same + * default behavior in interface Iterator itself can be provided. + * + * @author Taras Ledkov + */ +public class ArrayIterator { + + /** Close the constructor because ArrayIterator is part of the utility + * class. + */ + protected ArrayIterator() { + throw new UnsupportedOperationException(); + } + + /** + * Returns an iterator that goes over the elements in the array. + * + * @param type of an array element + * @param array source array to iterate over it + * @return an iterator that goes over the elements in the array + */ + public static Iterator iterator(final E[] array) { + return new Iterator() { + /** + * Initial array + * + */ + private final E[] srcArray = array; + + /** + * Index of the current position + * + */ + private int index = 0; + + /** + * Returns the next element in the iteration + * + * @return the next element in the iteration + * @throws NoSuchElementException if the iteration has no more + * elements + */ + @Override + public boolean hasNext() { + return (index < srcArray.length); + } + + /** + * Returns {@code true} if the iteration has more elements. (In + * other words, returns {@code true} if {@link #next} returns + * an element, rather than throwing an exception.) + * + * @return {@code true} if the iteration has more elements + */ + @Override + public E next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } + return srcArray[index++]; + } + + /** + * This method does not need to be overwritten in JDK 8. + */ + //@Override + //public void remove() { + // throw UnsupportedOperationException( + // "Arrays don't support remove.") + //} + }; + } + + /** + * Sample usage of the ArrayIterator + * + * @param args command-line arguments + */ + public static void main(final String[] args) { + Iterator it = ArrayIterator.iterator( + new String[]{"one", "two", "three"}); + + while (it.hasNext()) { + System.out.println(it.next()); + } + } +}