001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.directory.shared.util; 021 022 023import java.util.Iterator; 024import java.util.NoSuchElementException; 025 026import org.apache.directory.shared.i18n.I18n; 027 028 029/** 030 * An Iterator that joins the results of many iterators. 031 * 032 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 033 */ 034public class JoinIterator implements Iterator<Object> 035{ 036 /** the iterators whose results are joined */ 037 private final Iterator<?>[] iterators; 038 039 private int index; 040 041 042 /** 043 * Creates an Iterator that joins other Iterators. 044 * 045 * @param iterators 046 * the Iterators whose results are joined 047 * @throws IllegalArgumentException 048 * if a null array argument, or one with less than 2 elements is 049 * used 050 */ 051 public JoinIterator( Iterator<?>[] iterators ) 052 { 053 if ( iterators == null || iterators.length < 2 ) 054 { 055 throw new IllegalArgumentException( I18n.err( I18n.ERR_04397 ) ); 056 } 057 058 this.iterators = new Iterator[ iterators.length ]; 059 System.arraycopy( iterators, 0, this.iterators, 0, iterators.length ); 060 this.index = 0; 061 } 062 063 064 public void remove() 065 { 066 throw new UnsupportedOperationException(); 067 } 068 069 070 public boolean hasNext() 071 { 072 for ( /** nada */ 073 ; index < iterators.length; index++ ) 074 { 075 if ( iterators[index].hasNext() ) 076 { 077 return true; 078 } 079 } 080 081 return false; 082 } 083 084 085 public Object next() 086 { 087 for ( /** nada */ 088 ; index < iterators.length; index++ ) 089 { 090 if ( iterators[index].hasNext() ) 091 { 092 return iterators[index].next(); 093 } 094 } 095 096 throw new NoSuchElementException(); 097 } 098}