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Java example source code file (SequenceInputStream.java)
The SequenceInputStream.java Java example source code/* * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.io; import java.io.InputStream; import java.util.Enumeration; import java.util.Vector; /** * A <code>SequenceInputStream represents * the logical concatenation of other input * streams. It starts out with an ordered * collection of input streams and reads from * the first one until end of file is reached, * whereupon it reads from the second one, * and so on, until end of file is reached * on the last of the contained input streams. * * @author Author van Hoff * @since JDK1.0 */ public class SequenceInputStream extends InputStream { Enumeration<? extends InputStream> e; InputStream in; /** * Initializes a newly created <code>SequenceInputStream * by remembering the argument, which must * be an <code>Enumeration that produces * objects whose run-time type is <code>InputStream. * The input streams that are produced by * the enumeration will be read, in order, * to provide the bytes to be read from this * <code>SequenceInputStream. After * each input stream from the enumeration * is exhausted, it is closed by calling its * <code>close method. * * @param e an enumeration of input streams. * @see java.util.Enumeration */ public SequenceInputStream(Enumeration<? extends InputStream> e) { this.e = e; try { nextStream(); } catch (IOException ex) { // This should never happen throw new Error("panic"); } } /** * Initializes a newly * created <code>SequenceInputStream * by remembering the two arguments, which * will be read in order, first <code>s1 * and then <code>s2, to provide the * bytes to be read from this <code>SequenceInputStream. * * @param s1 the first input stream to read. * @param s2 the second input stream to read. */ public SequenceInputStream(InputStream s1, InputStream s2) { Vector<InputStream> v = new Vector<>(2); v.addElement(s1); v.addElement(s2); e = v.elements(); try { nextStream(); } catch (IOException ex) { // This should never happen throw new Error("panic"); } } /** * Continues reading in the next stream if an EOF is reached. */ final void nextStream() throws IOException { if (in != null) { in.close(); } if (e.hasMoreElements()) { in = (InputStream) e.nextElement(); if (in == null) throw new NullPointerException(); } else in = null; } /** * Returns an estimate of the number of bytes that can be read (or * skipped over) from the current underlying input stream without * blocking by the next invocation of a method for the current * underlying input stream. The next invocation might be * the same thread or another thread. A single read or skip of this * many bytes will not block, but may read or skip fewer bytes. * <p> * This method simply calls {@code available} of the current underlying * input stream and returns the result. * * @return an estimate of the number of bytes that can be read (or * skipped over) from the current underlying input stream * without blocking or {@code 0} if this input stream * has been closed by invoking its {@link #close()} method * @exception IOException if an I/O error occurs. * * @since JDK1.1 */ public int available() throws IOException { if(in == null) { return 0; // no way to signal EOF from available() } return in.available(); } /** * Reads the next byte of data from this input stream. The byte is * returned as an <code>int in the range Other Java examples (source code examples)Here is a short list of links related to this Java SequenceInputStream.java source code file: |
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