Впритык не вижу, что не так
package com.javarush.task.task18.task1826;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
/*
Шифровка
*/
public class Solution {
public static void main(String[] args) throws IOException {
String str = args[0];
FileInputStream fileInputStream = new FileInputStream(args[1]);
FileOutputStream fileOutputStream = new FileOutputStream(args[2]);
if (str.equals("-e") || args.length != 0) {
while (fileInputStream.available() > 0) {
fileOutputStream.write(fileInputStream.read() / 128);
}
}
else if (str.equals("-d") || args.length != 0) {
while (fileInputStream.available() > 0) {
fileOutputStream.write(fileInputStream.read() * 128);
}
}
fileInputStream.close();
fileOutputStream.close();
}
}