Прв колоквиум(Група 1) - ОС

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.List;

public class PrvKolokvium_Grupa1 {
    public  void moveWritableTxtFiles(String from, String to){
        File f = new File(from);
        File t = new File(to);

        if(!f.exists()){
            System.out.println("Ne postoi");
            return;
        }
        if(!t.exists()){
            t.mkdirs();
        }

        File[] files = f.listFiles();
        for (File file : files) {
            if(file.getName().endsWith(".txt") && file.canWrite()){
                File newFile = new File(to, file.getName());
                file.renameTo(newFile);
            }
        }

    }
    public void deserializeData(String source, List<byte[]> data, long elementLength) throws IOException{
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(source);
            byte[] element = new byte[(int) elementLength];
            int b;
            int counter =0;
            while((b = fis.read()) == -1){
                element[counter] = (byte) b;
                counter++;
                if(counter == elementLength){
                    data.add(element);
                    counter = 0;
                    element = new byte[ (int) elementLength];
                }
            }
        } catch (Exception e) {
            // TODO: handle exception
        } finally{
            if(fis != null)
                fis.close();
        }
    }
    public static void invertLargeFile(String source, String destination) throws IOException{

        RandomAccessFile rr = null;
        RandomAccessFile rw = null;
        try {
            rr = new RandomAccessFile(source, "r");
            rw = new RandomAccessFile(destination, "rw");
            long pos = rr.length() - 1;

            while(pos >= 0){
                rw.seek(pos);
                char c = (char) rr.read();
                rw.write(c);
                pos -= 1;
            }

        } catch (Exception e) {
            // TODO: handle exception
        }finally{
            if(rr != null){
                rr.close();
            }
            if(rw != null){
                rw.close();
            }
        }

    }
    public static void main(String[] args) throws IOException {

        File s = new File("source.txt");
        File d = new File("destinacija.txt");

        invertLargeFile(s.getName(), d.getName());
    }

}