Кто-нибудь разбирается в Java?

Скрытый текст:
package sce2000;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.io.FileUtils;

public class Sce2000 {
 
 public static final String SC2000DAT = "sc2000.dat";
 public static final int NUMFILES = 399;
 
 public static class Filestrut implements Serializable {
 private static final long serialVersionUID = 1L;
 public String filename;
 public int offset;
 public int targetOffset;
 }

 public static void main(String[] args) throws IOException, ClassNotFoundException {
 
 if (args.length == 0) {
 info();
 } else if ("x".equals(args[0])) {
 extract();
 } else if ("c".equals(args[0])) {
 create();
 } else {
 info();
 }

 }
 
 public static void info() {
 System.out.println("Usage: x to eXtract or c to Create (after eXtract) + sc2000.dat file");
 }

 public static void create() throws IOException, ClassNotFoundException {
 
 File sc2000dat = new File(SC2000DAT);
 File metafile = new File(SC2000DAT + "!/meta");
 ObjectInputStream ois = new ObjectInputStream(new FileInputStream(metafile));
 List<Filestrut> files = (List<Filestrut>) ois.readObject();
 
 List<Byte> targetFile = new ArrayList<Byte>();

 for (Filestrut file : files) {
 byte[] fileNameBytes = file.filename.getBytes(StandardCharsets.US_ASCII);
 for (Byte myByte : fileNameBytes) {
 targetFile.add(myByte);
 }
 for (int i = 0; i < 16 - fileNameBytes.length; i++) {
 targetFile.add((byte) 0);
 }
 //sourceFile.length();
 }
 
 int i = 0;
 for (Filestrut file : files) {
 byte[] binary = Files.readAllBytes(Paths.get(SC2000DAT + "!/" + file.filename));
 int fileOffset = targetFile.size();
 for (Byte myByte : binary) {
 targetFile.add(myByte);
 }
 int filePointer = 12 + (16 * i);
 
 byte[] offsetBytes = fromInt(fileOffset);
 targetFile.set(filePointer, offsetBytes[0]);
 targetFile.set(filePointer + 1, offsetBytes[1]);
 targetFile.set(filePointer + 2, offsetBytes[2]);
 targetFile.set(filePointer + 3, offsetBytes[3]);
 
 i++;
 }
 
 byte[] binaryFile = new byte[targetFile.size()];
 for (i = 0; i < targetFile.size(); i++) {
 binaryFile[i] = targetFile.get(i);
 }
 
 FileUtils.writeByteArrayToFile(sc2000dat, binaryFile);

 
 System.out.println();
 
 }
 

 public static void extract() throws IOException {
 
 Path sc2000dat = Paths.get(SC2000DAT);
 byte[] data = Files.readAllBytes(sc2000dat);
 
 int vector = 0;
 List<Filestrut> files = new ArrayList<Filestrut>();
 for (int i = 0; i < NUMFILES; i++) {
 
 Filestrut currfile = new Filestrut();
 
 currfile.filename = convertFilename(Arrays.copyOfRange(data, vector, vector + 12));
 vector += 12;
 
 currfile.offset = fromByteArray(Arrays.copyOfRange(data, vector, vector + 4));
 vector += 4;
 
 System.out.println("Found file " + currfile.filename + " at " + currfile.offset);
 
 files.add(currfile);
 
 }
 
 File dir = new File(SC2000DAT + "!");
 if (dir.exists()) {
 FileUtils.deleteDirectory(dir);
 }
 
 dir.mkdir();
 
 Iterator<Filestrut> fileIt = files.iterator();
 
 Filestrut file = fileIt.next();
 Filestrut fileNext = null;
 
 boolean stop = false;
 while (!stop) {
 
 File extracted = new File(SC2000DAT + "!/" + file.filename);
 
 int init = file.offset;
 int end = -1;
 if (fileIt.hasNext()) {
 fileNext = fileIt.next();
 end = fileNext.offset;
 } else {
 end = data.length;
 stop = true;
 }

 System.out.println("Writing: " + extracted.getAbsolutePath());
 FileUtils.writeByteArrayToFile(extracted, Arrays.copyOfRange(data, init, end));
 
 file = fileNext;
 
 }
 
 File metafile = new File(SC2000DAT + "!/meta");
 
 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(metafile));
 oos.writeObject(files);
 oos.close();
 
 System.out.println("OK!");
 }
 
 public static byte[] fromInt(int number) {
 byte[] bytes = ByteBuffer.allocate(4).putInt(number).array();
 swapEndianess(bytes);
 return bytes;
 }
 
 public static void swapEndianess(byte [] bytes) {
 byte temp1 = bytes[0];
 byte temp2 = bytes[1];
 bytes[0] = bytes[3];
 bytes[1] = bytes[2];
 bytes[2] = temp2;
 bytes[3] = temp1;
 }
 
 public static int fromByteArray(byte[] bytes) {
 // Change endianness
 swapEndianess(bytes);
 return ByteBuffer.wrap(bytes).getInt();
 }
 
 public static String convertFilename(byte[] data) {
 StringBuilder sb = new StringBuilder(data.length);
 for (int i = 0; i < data.length; ++ i) {
 if (data[i] < 0) {
 throw new IllegalArgumentException();
 }
 if (data[i] == 0) {
 break;
 }
 sb.append((char) data[i]);
 }
 return sb.toString();
 }


}