01: /*
02: * <copyright>
03: *
04: * Copyright 2002-2004 BBNT Solutions, LLC
05: * under sponsorship of the Defense Advanced Research Projects
06: * Agency (DARPA).
07: *
08: * You can redistribute this software and/or modify it under the
09: * terms of the Cougaar Open Source License as published on the
10: * Cougaar Open Source Website (www.cougaar.org).
11: *
12: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
13: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
14: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
15: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
16: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
17: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
18: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
22: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: *
24: * </copyright>
25: */
26:
27: package org.cougaar.util;
28:
29: import java.util.Iterator;
30: import java.util.NoSuchElementException;
31:
32: /** An Iterator implementation which successively iterates over
33: * a list of iterators.
34: **/
35: public class ChainingIterator implements Iterator {
36: private Iterator[] its;
37: private int i = 0;
38: private int l;
39: private Object nextOne = null;
40: private boolean hasNext = true; // gets set to false by advance if empty
41:
42: public ChainingIterator(Iterator[] its) {
43: this .its = its;
44: l = its.length;
45: advance();
46: }
47:
48: private void advance() {
49: while (i < l) { // as long as we have iterators
50: // check the current iterator
51: Iterator c = its[i];
52:
53: // null iterator? advance iterators
54: if (c == null) {
55: i++;
56: continue;
57: }
58:
59: // anything left on the current iterator?
60: if (c.hasNext()) {
61: nextOne = c.next();
62: return;
63: }
64:
65: // nope - advance
66: i++;
67: }
68: hasNext = false;
69: }
70:
71: public final boolean hasNext() {
72: return hasNext;
73: }
74:
75: public final Object next() {
76: if (hasNext) {
77: Object o = nextOne;
78: advance();
79: return o;
80: } else {
81: throw new NoSuchElementException();
82: }
83: }
84:
85: public final void remove() {
86: throw new UnsupportedOperationException();
87: }
88: }
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