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 */ 020 package org.apache.directory.shared.ldap.util; 021 022 023 import java.util.Iterator; 024 import java.util.NoSuchElementException; 025 026 import 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 * @version $Rev: 919765 $ 034 */ 035 public class JoinIterator implements Iterator 036 { 037 /** the iterators whose results are joined */ 038 private final Iterator[] iterators; 039 040 private int index; 041 042 043 /** 044 * Creates an Iterator that joins other Iterators. 045 * 046 * @param iterators 047 * the Iterators whose results are joined 048 * @throws IllegalArgumentException 049 * if a null array argument, or one with less than 2 elements is 050 * used 051 */ 052 public JoinIterator(Iterator[] iterators) 053 { 054 if ( iterators == null || iterators.length < 2 ) 055 { 056 throw new IllegalArgumentException( I18n.err( I18n.ERR_04397 ) ); 057 } 058 059 if ( iterators != null ) 060 { 061 this.iterators = new Iterator[ iterators.length ]; 062 System.arraycopy( iterators, 0, this.iterators, 0, iterators.length ); 063 } else { 064 this.iterators = null; 065 } 066 this.index = 0; 067 } 068 069 070 public void remove() 071 { 072 throw new UnsupportedOperationException(); 073 } 074 075 076 public boolean hasNext() 077 { 078 for ( /** nada */ 079 ; index < iterators.length; index++ ) 080 { 081 if ( iterators[index].hasNext() ) 082 { 083 return true; 084 } 085 } 086 087 return false; 088 } 089 090 091 public Object next() 092 { 093 for ( /** nada */ 094 ; index < iterators.length; index++ ) 095 { 096 if ( iterators[index].hasNext() ) 097 { 098 return iterators[index].next(); 099 } 100 } 101 102 throw new NoSuchElementException(); 103 } 104 }