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Java > Open Source Codes > org > jboss > util > collection > CompoundIterator


1 /*
2   * JBoss, Home of Professional Open Source
3   * Copyright 2005, JBoss Inc., and individual contributors as indicated
4   * by the @authors tag. See the copyright.txt in the distribution for a
5   * full listing of individual contributors.
6   *
7   * This is free software; you can redistribute it and/or modify it
8   * under the terms of the GNU Lesser General Public License as
9   * published by the Free Software Foundation; either version 2.1 of
10   * the License, or (at your option) any later version.
11   *
12   * This software is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this software; if not, write to the Free
19   * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20   * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21   */
22 package org.jboss.util.collection;
23
24 import java.util.Iterator JavaDoc;
25 import java.util.NoSuchElementException JavaDoc;
26
27 /**
28  * A compound iterator, which iterates over all of the elements in the
29  * given iterators.
30  *
31  * @version <tt>$Revision: 1958 $</tt>
32  * @author <a HREF="mailto:jason@planet57.com">Jason Dillon</a>
33  */
34 public class CompoundIterator
35    implements Iterator JavaDoc
36 {
37    /** The array of iterators to iterate over. */
38    protected final Iterator JavaDoc iters[];
39
40    /** The index of the current iterator. */
41    protected int index;
42
43    /**
44     * Construct a CompoundIterator over the given array of iterators.
45     *
46     * @param iters Array of iterators to iterate over.
47     *
48     * @throws IllegalArgumentException Array is <kk>null</kk> or empty.
49     */
50    public CompoundIterator(final Iterator JavaDoc iters[]) {
51       if (iters == null || iters.length == 0)
52          throw new IllegalArgumentException JavaDoc("array is null or empty");
53      
54       this.iters = iters;
55    }
56
57    /**
58     * Check if there are more elements.
59     *
60     * @return True if there are more elements.
61     */
62    public boolean hasNext() {
63       for (; index < iters.length; index++) {
64          if (iters[index] != null && iters[index].hasNext()) {
65             return true;
66          }
67       }
68
69       return false;
70    }
71
72    /**
73     * Return the next element from the current iterator.
74     *
75     * @return The next element from the current iterator.
76     *
77     * @throws NoSuchElementException There are no more elements.
78     */
79    public Object JavaDoc next() {
80       if (!hasNext()) {
81          throw new NoSuchElementException JavaDoc();
82       }
83
84       return iters[index].next();
85    }
86
87    /**
88     * Remove the current element from the current iterator.
89     *
90     * @throws IllegalStateException
91     * @throws UnsupportedOperationException
92     */
93    public void remove() {
94       iters[index].remove();
95    }
96 }
97
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