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