001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.collections.primitives.adapters.io; 018 019import java.io.IOException; 020import java.io.Reader; 021import java.util.NoSuchElementException; 022 023import org.apache.commons.collections.primitives.CharIterator; 024 025/** 026 * Adapts a {@link Reader} to the {@link CharIterator} interface. 027 * 028 * @version $Revision: 480462 $ $Date: 2006-11-29 03:15:00 -0500 (Wed, 29 Nov 2006) $ 029 * @author Rodney Waldhoff 030 */ 031public class ReaderCharIterator implements CharIterator { 032 033 public ReaderCharIterator(Reader in) { 034 this.reader = in; 035 } 036 037 public static CharIterator adapt(Reader in) { 038 return null == in ? null : new ReaderCharIterator(in); 039 } 040 041 public boolean hasNext() { 042 ensureNextAvailable(); 043 return (-1 != next); 044 } 045 046 public char next() { 047 if(!hasNext()) { 048 throw new NoSuchElementException("No next element"); 049 } else { 050 nextAvailable = false; 051 return (char)next; 052 } 053 } 054 055 /** 056 * Not supported. 057 * @throws UnsupportedOperationException 058 */ 059 public void remove() throws UnsupportedOperationException { 060 throw new UnsupportedOperationException("remove() is not supported here"); 061 } 062 063 private void ensureNextAvailable() { 064 if(!nextAvailable) { 065 readNext(); 066 } 067 } 068 069 private void readNext() { 070 try { 071 next = reader.read(); 072 nextAvailable = true; 073 } catch(IOException e) { 074 // TODO: Use a tunnelled exception instead? 075 // See http://radio.weblogs.com/0122027/2003/04/01.html#a7, for example 076 throw new RuntimeException(e.toString()); 077 } 078 } 079 080 private Reader reader = null; 081 private boolean nextAvailable = false; 082 private int next; 083 084}