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package com.github.coderodde.file.util;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
/**
 * This class implements a program for counting byte histograms in files.
 * 
 * @version 1.0.0 (Nov 13, 2024)
 * @since 1.0.0 (Nov 13, 2024)
 */
public final class ByteHistogramApp {
 public static void main(String[] args) {
 List<InputStream> inputStreamList = null;
 
 // Prepare the input streams from which to build the (shared) byte 
 // histogram:
 try {
 inputStreamList = getInputStreams(args);
 } catch (final PairException ex) {
 
 ex.getFileNotFoundException()
 .getExceptionList()
 .forEach((e) -> System.err.println(e.getMessage()));
 
 ex.getIOException()
 .getExceptionList()
 .forEach((e) -> System.err.println(e.getMessage()));
 
 System.exit(-1);
 }
 
 // Once here, we have valid input streams. Request the histogram and 
 // print it in the console:
 try {
 System.out.println(processInputStreamList(inputStreamList));
 } catch (MultipleIOException ex) {
 
 ex.getExceptionList()
 .forEach((e) -> System.err.println(e.getMessage()));
 
 System.exit(-2);
 }
 }
 
 /**
 * Converts the input argument list to the list of input streams.
 * 
 * @param args the names of the files to process.
 * 
 * @return the input stream list.
 * 
 * @throws MultipleFileNotFoundException if any file failed.
 */
 private static List<InputStream> getInputStreams(final String[] args)
 throws PairException {
 
 if (args.length == 0) {
 return List.of(System.in);
 }
 
 final List<InputStream> inputStreamList = new ArrayList<>(args.length);
 
 final MultipleFileNotFoundException exceptionListFileNotFound = 
 new MultipleFileNotFoundException();
 
 final MultipleIOException exceptionListIO =
 new MultipleIOException();
 
 for (final String fileName : args) {
 try {
 final InputStream is = new FileInputStream(new File(fileName));
 inputStreamList.add(is);
 } catch (final FileNotFoundException ex) {
 // Add the exception ex to the exceptionList:
 exceptionListFileNotFound.add(ex);
 
 for (final InputStream is : inputStreamList) {
 try {
 is.close();
 } catch (final IOException ioException) {
 exceptionListIO.add(ioException);
 }
 }
 }
 }
 
 if (!exceptionListIO.isEmpty() || 
 !exceptionListFileNotFound.isEmpty()) {
 // Once here, something went wrong. Throw:
 
 throw new PairException(exceptionListFileNotFound,
 exceptionListIO);
 }
 
 return inputStreamList;
 }
 
 /**
 * Builds the shared histogram from the input streams in the argument.
 * 
 * @param inputStreamList the list of input stream supplying the bytes.
 * 
 * @return the shared byte histogram.
 * 
 * @throws MultipleIOException if any stream threw.
 */
 private static ByteHistogram
 processInputStreamList(final List<InputStream> inputStreamList) 
 throws MultipleIOException {
 
 final ByteHistogram histogram = new ByteHistogram();
 final MultipleIOException ex = new MultipleIOException();
 
 for (final InputStream is : inputStreamList) {
 try {
 processInputStream(
 new BufferedInputStream(is), 
 histogram);
 
 } catch (final IOException e) {
 // Add the new I/O exception e to ex::
 ex.add(e);
 }
 }
 
 if (!ex.isEmpty()) {
 // Once here, something went wrong. Throw:
 throw ex;
 }
 
 return histogram;
 }
 
 /**
 * Processes the input stream reading bytes from it until end of file is 
 * reached.
 * 
 * @param is the input stream.
 * @param histogram the target histogram.
 * 
 * @throws IOException if I/O fails.
 */
 private static void processInputStream(final InputStream is,
 final ByteHistogram histogram) 
 throws IOException {
 
 int i;
 
 while ((i = is.read()) != -1) {
 histogram.insert(i);
 }
 
 is.close();
 }
}

com.github.coderodde.file.util.ByteHistogram.java:

package com.github.coderodde.file.util;
/**
 * This class implements the byte histogram.
 * 
 * @version 1.0.0 (Nov 13, 2024)
 * @since 1.0.0 (Nov 13, 2024)
 */
public final class ByteHistogram {
 
 private static final int HISTOGRAM_CAPACITY = 256;
 private static final int SCREEN_WIDTH = 80;
 private static final int LINE_PREAMBLE_WIDTH = 11;
 
 private final long[] data = new long[HISTOGRAM_CAPACITY];
 
 /**
 * Account the byte {@code b}.
 * 
 * @param b the byte to account. 
 */
 public void insert(final int b) {
 data[b]++;
 }
 
 /**
 * Converts this byte histogram to an ASCII art.
 * 
 * @return ASCII art version of this byte histogram. 
 */
 @Override
 public String toString() {
 final StringBuilder sb = new StringBuilder();
 final long maximumCount = computeMaximumCount();
 final int countStringLength = 
 computeCountStringLength(maximumCount);
 
 final String lineFormat = getLineFormat(countStringLength);
 
 for (int i = 0; i < data.length; i++) {
 loadLine(sb,
 lineFormat,
 countStringLength,
 i,
 maximumCount);
 }
 
 return sb.toString();
 }
 
 /**
 * Builds the format for printing the lines in the output.
 * 
 * @param countStringLength the count string length in characters.
 * 
 * @return the format for printing the lines in the output.
 */
 private static String getLineFormat(final int countStringLength) {
 return String.format("0x%%02x [%%c]: %% %dd %%s\n", countStringLength);
 }
 
 /**
 * Loads a single line to the total output of this byte histogram.
 * 
 * @param sb the string builder.
 * @param lineFormat the format of the line.
 * @param countStringLength the length of the count string.
 * @param index the byte index.
 * @param maximumCount the maximum count in the histogram.
 */
 private void loadLine(final StringBuilder sb, 
 final String lineFormat,
 final int countStringLength,
 final int index, 
 final long maximumCount) {
 
 sb.append(
 String.format(
 lineFormat,
 index, 
 !Character.isISOControl((char) index) ?
 (char) index : 
 '?',
 data[index],
 computeBarAscii(data[index],
 maximumCount,
 countStringLength)));
 }
 
 /**
 * Computes and returns the bar ASCII art.
 * 
 * @param count the count of the line we are processing.
 * @param maximumCount the maximum count in the byte histogram.
 * @param countStringLength the count string length.
 * 
 * @return the bar ASCII art. 
 */
 private static String computeBarAscii(final long count,
 final long maximumCount,
 final int countStringLength) {
 
 final float ratio = ((float) count) / ((float) maximumCount);
 
 final int maximumBarLength = SCREEN_WIDTH
 - LINE_PREAMBLE_WIDTH 
 - countStringLength;
 
 final int barLength = (int)(ratio * maximumBarLength);
 
 final StringBuilder sb = new StringBuilder(barLength);
 
 for (int i = 0; i < barLength; i++) {
 sb.append("*");
 }
 
 return sb.toString();
 }
 
 /**
 * Computes the maximum count in this byte histogram.
 * 
 * @return the maximum count.
 */
 private long computeMaximumCount() {
 long m = 0L;
 
 for (final long count : data) {
 m = Math.max(m, count);
 }
 
 return m;
 }
 
 /**
 * Computes and returns the length of the widest length string.
 * 
 * @param maximumLength the maximum length of the byte histogram.
 * 
 * @return the widest length of the count string in characters.
 */
 private static int computeCountStringLength(final long maximumLength) {
 return Long.toString(maximumLength).length();
 }
}

Typical output

C:\Users\rodio\OneDrive\Documents\NetBeansProjects\ByteHistogram.java\target\classes>echo Hello World | java com.github.coderodde.file.util.ByteHistogramApp
0x00 [?]: 0
0x01 [?]: 0
0x02 [?]: 0
0x03 [?]: 0
0x04 [?]: 0
0x05 [?]: 0
0x06 [?]: 0
0x07 [?]: 0
0x08 [?]: 0
0x09 [?]: 0
0x0a [?]: 1 **********************
0x0b [?]: 0
0x0c [?]: 0
0x0d [?]: 1 **********************
0x0e [?]: 0
0x0f [?]: 0
0x10 [?]: 0
0x11 [?]: 0
0x12 [?]: 0
0x13 [?]: 0
0x14 [?]: 0
0x15 [?]: 0
0x16 [?]: 0
0x17 [?]: 0
0x18 [?]: 0
0x19 [?]: 0
0x1a [?]: 0
0x1b [?]: 0
0x1c [?]: 0
0x1d [?]: 0
0x1e [?]: 0
0x1f [?]: 0
0x20 [ ]: 2 *********************************************
0x21 [!]: 0
0x22 ["]: 0
0x23 [#]: 0
0x24 [$]: 0
0x25 [%]: 0
0x26 [&]: 0
0x27 [']: 0
0x28 [(]: 0
0x29 [)]: 0
0x2a [*]: 0
0x2b [+]: 0
0x2c [,]: 0
0x2d [-]: 0
0x2e [.]: 0
0x2f [/]: 0
0x30 [0]: 0
0x31 [1]: 0
0x32 [2]: 0
0x33 [3]: 0
0x34 [4]: 0
0x35 [5]: 0
0x36 [6]: 0
0x37 [7]: 0
0x38 [8]: 0
0x39 [9]: 0
0x3a [:]: 0
0x3b [;]: 0
0x3c [<]: 0
0x3d [=]: 0
0x3e [>]: 0
0x3f [?]: 0
0x40 [@]: 0
0x41 [A]: 0
0x42 [B]: 0
0x43 [C]: 0
0x44 [D]: 0
0x45 [E]: 0
0x46 [F]: 0
0x47 [G]: 0
0x48 [H]: 1 **********************
0x49 [I]: 0
0x4a [J]: 0
0x4b [K]: 0
0x4c [L]: 0
0x4d [M]: 0
0x4e [N]: 0
0x4f [O]: 0
0x50 [P]: 0
0x51 [Q]: 0
0x52 [R]: 0
0x53 [S]: 0
0x54 [T]: 0
0x55 [U]: 0
0x56 [V]: 0
0x57 [W]: 1 **********************
0x58 [X]: 0
0x59 [Y]: 0
0x5a [Z]: 0
0x5b [[]: 0
0x5c [\]: 0
0x5d []]: 0
0x5e [^]: 0
0x5f [_]: 0
0x60 [`]: 0
0x61 [a]: 0
0x62 [b]: 0
0x63 [c]: 0
0x64 [d]: 1 **********************
0x65 [e]: 1 **********************
0x66 [f]: 0
0x67 [g]: 0
0x68 [h]: 0
0x69 [i]: 0
0x6a [j]: 0
0x6b [k]: 0
0x6c [l]: 3 ********************************************************************
0x6d [m]: 0
0x6e [n]: 0
0x6f [o]: 2 *********************************************
0x70 [p]: 0
0x71 [q]: 0
0x72 [r]: 1 **********************
0x73 [s]: 0
0x74 [t]: 0
0x75 [u]: 0
0x76 [v]: 0
0x77 [w]: 0
0x78 [x]: 0
0x79 [y]: 0
0x7a [z]: 0
0x7b [{]: 0
0x7c [|]: 0
0x7d [}]: 0
0x7e [~]: 0
0x7f [?]: 0
0x80 [?]: 0
0x81 [?]: 0
0x82 [?]: 0
0x83 [?]: 0
0x84 [?]: 0
0x85 [?]: 0
0x86 [?]: 0
0x87 [?]: 0
0x88 [?]: 0
0x89 [?]: 0
0x8a [?]: 0
0x8b [?]: 0
0x8c [?]: 0
0x8d [?]: 0
0x8e [?]: 0
0x8f [?]: 0
0x90 [?]: 0
0x91 [?]: 0
0x92 [?]: 0
0x93 [?]: 0
0x94 [?]: 0
0x95 [?]: 0
0x96 [?]: 0
0x97 [?]: 0
0x98 [?]: 0
0x99 [?]: 0
0x9a [?]: 0
0x9b [?]: 0
0x9c [?]: 0
0x9d [?]: 0
0x9e [?]: 0
0x9f [?]: 0
0xa0 [ ]: 0
0xa1 [¡]: 0
0xa2 [¢]: 0
0xa3 [£]: 0
0xa4 [¤]: 0
0xa5 [\]: 0
0xa6 [¦]: 0
0xa7 [§]: 0
0xa8 [ ̈]: 0
0xa9 [©]: 0
0xaa [a]: 0
0xab [«]: 0
0xac [¬]: 0
0xad []: 0
0xae [®]: 0
0xaf [ ̄]: 0
0xb0 [°]: 0
0xb1 [±]: 0
0xb2 [2]: 0
0xb3 [3]: 0
0xb4 [ ́]: 0
0xb5 [μ]: 0
0xb6 [¶]: 0
0xb7 [·]: 0
0xb8 [ ̧]: 0
0xb9 [1]: 0
0xba [o]: 0
0xbb [»]: 0
0xbc [1⁄4]: 0
0xbd [1⁄2]: 0
0xbe [3⁄4]: 0
0xbf [¿]: 0
0xc0 [À]: 0
0xc1 [Á]: 0
0xc2 [Â]: 0
0xc3 [Ã]: 0
0xc4 [Ä]: 0
0xc5 [Å]: 0
0xc6 [Æ]: 0
0xc7 [Ç]: 0
0xc8 [È]: 0
0xc9 [É]: 0
0xca [Ê]: 0
0xcb [Ë]: 0
0xcc [Ì]: 0
0xcd [Í]: 0
0xce [Î]: 0
0xcf [Ï]: 0
0xd0 [Ð]: 0
0xd1 [Ñ]: 0
0xd2 [Ò]: 0
0xd3 [Ó]: 0
0xd4 [Ô]: 0
0xd5 [Õ]: 0
0xd6 [Ö]: 0
0xd7 ×ばつ]: 0
0xd8 [Ø]: 0
0xd9 [Ù]: 0
0xda [Ú]: 0
0xdb [Û]: 0
0xdc [Ü]: 0
0xdd [Ý]: 0
0xde [Þ]: 0
0xdf [ß]: 0
0xe0 [à]: 0
0xe1 [á]: 0
0xe2 [â]: 0
0xe3 [ã]: 0
0xe4 [ä]: 0
0xe5 [å]: 0
0xe6 [æ]: 0
0xe7 [ç]: 0
0xe8 [è]: 0
0xe9 [é]: 0
0xea [ê]: 0
0xeb [ë]: 0
0xec [ì]: 0
0xed [í]: 0
0xee [î]: 0
0xef [ï]: 0
0xf0 [ð]: 0
0xf1 [ñ]: 0
0xf2 [ò]: 0
0xf3 [ó]: 0
0xf4 [ô]: 0
0xf5 [õ]: 0
0xf6 [ö]: 0
0xf7 [÷]: 0
0xf8 [ø]: 0
0xf9 [ù]: 0
0xfa [ú]: 0
0xfb [û]: 0
0xfc [ü]: 0
0xfd [ý]: 0
0xfe [þ]: 0
0xff [ÿ]: 0

Critique request

Please tell me anything that comes to mind.

java file statistics byte

lang-java