HexDump.java

Below is the syntax highlighted version of HexDump.java.

/******************************************************************************
 *  Compilation:  javac HexDump.java
 *  Execution:    java HexDump < file
 *  Dependencies: BinaryStdIn.java StdOut.java
 *  Data file:    https://algs4.cs.princeton.edu/55compression/abra.txt
 *
 *  Reads in a binary file and writes out the bytes in hex, 16 per line.
 *
 *  % more abra.txt
 *  ABRACADABRA!
 *
 *  % java HexDump 16 < abra.txt
 *  41 42 52 41 43 41 44 41 42 52 41 21
 *  96 bits
 *
 *
 *  Remark
 *  --------------------------
 *   - Similar to the Unix utilities od (octal dump) or hexdump (hexadecimal dump).
 *
 *  % od -t x1 < abra.txt
 *  0000000 41 42 52 41 43 41 44 41 42 52 41 21
 *  0000014
 *
 ******************************************************************************/

package edu.princeton.cs.algs4;

/**
 *  The {@code HexDump} class provides a client for displaying the contents
 *  of a binary file in hexadecimal.
 *  <p>
 *  For additional documentation,
 *  see <a href="https://algs4.cs.princeton.edu/55compression">Section 5.5</a> of
 *  <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
 *  <p>
 *  See also {@link BinaryDump} and {@link PictureDump}.
 *  For more full-featured versions, see the Unix utilities
 *  {@code od} (octal dump) and {@code hexdump} (hexadecimal dump).
 *  <p>
 *
 *  @author Robert Sedgewick
 *  @author Kevin Wayne
 */
public class HexDump {

    // Do not instantiate.
    private HexDump() { }

    /**
     * Reads in a sequence of bytes from standard input and writes
     * them to standard output using hexadecimal notation, k hex digits
     * per line, where k is given as a command-line integer (defaults
     * to 16 if no integer is specified); also writes the number
     * of bits.
     *
     * @param args the command-line arguments
     */
    public static void main(String[] args) {
        int bytesPerLine = 16;
        if (args.length == 1) {
            bytesPerLine = Integer.parseInt(args[0]);
        }

        int i;
        for (i = 0; !BinaryStdIn.isEmpty(); i++) {
            if (bytesPerLine == 0) {
                BinaryStdIn.readChar();
                continue;
            }
            if (i == 0) StdOut.printf("");
            else if (i % bytesPerLine == 0) StdOut.printf("\n", i);
            else StdOut.print(" ");
            char c = BinaryStdIn.readChar();
            StdOut.printf("%02x", c & 0xff);
        }
        if (bytesPerLine != 0) StdOut.println();
        StdOut.println((i*8) + " bits");
    }
}

/******************************************************************************
 *  Copyright 2002-2022, Robert Sedgewick and Kevin Wayne.
 *
 *  This file is part of algs4.jar, which accompanies the textbook
 *
 *      Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,
 *      Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.
 *      http://algs4.cs.princeton.edu
 *
 *
 *  algs4.jar is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  algs4.jar 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 for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with algs4.jar.  If not, see http://www.gnu.org/licenses.
 ******************************************************************************/