RandomRead.java Source code

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Here is the source code for RandomRead.java

Source

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */

import java.io.IOException;
import java.io.RandomAccessFile;

/**
 * Read a file containing an offset, and a String at that offset.
 * 
 * @author Ian F. Darwin, http://www.darwinsys.com/
 * @version $Id: ReadRandom.java,v 1.6 2004/03/07 17:30:35 ian Exp $
 */
public class RandomRead {
    final static String FILENAME = "random.dat";

    protected String fileName;

    protected RandomAccessFile seeker;

    public static void main(String[] argv) throws IOException {
        RandomRead r = new RandomRead(FILENAME);

        System.out.println("Offset is " + r.readOffset());
        System.out.println("Message is \"" + r.readMessage() + "\".");
    }

    /** Constructor: save filename, construct RandomAccessFile */
    public RandomRead(String fname) throws IOException {
        fileName = fname;
        seeker = new RandomAccessFile(fname, "r");
    }

    /** Read the Offset field, defined to be at location 0 in the file. */
    public int readOffset() throws IOException {
        seeker.seek(0); // move to very beginning
        return seeker.readInt(); // and read the offset
    }

    /** Read the message at the given offset */
    public String readMessage() throws IOException {
        seeker.seek(readOffset()); // move to the offset
        return seeker.readLine(); // and read the String
    }
}