Can someone help please ?

Question sur la mission

Division d'un fichier

Bases de Java, Niveau 8, Leçon 5

Résolues

I have indexOutOfBoundException + it says that I put larger part in third file and I don't know why ?

Lis 3 noms de fichier depuis la console : file1, file2 et file3.
Divise file1 comme suit :
Écris la première moitié de ses octets dans file2, et la seconde dans file3.
Si le nombre d'octets dans file1 est impair, file2 doit contenir la moitié la plus grande.
Ferme les flux.

Impératifs :

Le programme doit lire un nom de fichier trois fois depuis la console.
Utilise FileInputStream pour lire à partir d'un fichier, et FileOutputStream pour écrire dans des fichiers.
La première moitié des octets dans le premier fichier doit être écrite dans le deuxième fichier.
La seconde moitié des octets dans le premier fichier doit être écrite dans le troisième fichier.
Tu dois fermer FileInputStream et FileOutputStream.

package fr.codegym.task.task18.task1808; /* Division d'un fichier */ import java.io.*; public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String[] fichiers = new String[3]; for (int i=0 ; i < fichiers.length ; i++){ fichiers[i] = reader.readLine(); } FileInputStream inputStream = new FileInputStream(fichiers[0]); FileOutputStream outputStream1 = new FileOutputStream(fichiers[1]); FileOutputStream outputStream2 = new FileOutputStream(fichiers[2]); byte[] buffer = new byte[inputStream.available()]; while (inputStream.available() > 0){ int count = inputStream.read(buffer); if (count % 2 == 0) { outputStream1.write(buffer, 0, count/2); outputStream2.write(buffer, (count/2), count); } else if (count == 1){ outputStream2.write(buffer, 0, count); } else { outputStream1.write(buffer, 0, (count/2)+1); outputStream2.write(buffer, (count/2)+1, count); } } inputStream.close(); outputStream1.close(); outputStream2.close(); } }

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Artem Divertitto Senior Android Developer chez United Tech

27 avril 2020, 11:13

solution

outputStream2.write(buffer, (count/2), count);

Well, let's imagine, that count == 40, here you try to write to file from 20 byte to 60, and you will get IndexOutOfBoundsException.

outputStream2.write(buffer, (count/2)+1, count);

The same

thesouv

niveau Nice, Nice, France

27 avril 2020, 11:34

Oh I get it I was confusing between length and end, I thought it was end here .. Thanks

Nouser

, Germany

26 avril 2020, 14:21

Just a guess as I think the verification doesn't consider it... remove the check for 1 byte files

thesouv

niveau Nice, Nice, France

26 avril 2020, 15:51

No, it's still the same :(

Nouser

, Germany

26 avril 2020, 19:07

Hmm... unfortunately I can't try your code anymore but it still looks good to me. Mine is similar, not exactly the same but at least it does the same. I'll post it, maybe it helps you to find the problem.

String fileName1 = null, fileName2 = null, fileName3 = null;
try(BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
    fileName1 = reader.readLine();
    fileName2 = reader.readLine();
    fileName3 = reader.readLine();
} catch(IOException e) {
    e.printStackTrace();
}
//input stream, auto closes after try block
try (FileInputStream in = new FileInputStream(fileName1)) {
    //output streams for file2 and 3
    FileOutputStream out2 = new FileOutputStream(fileName2);
    FileOutputStream out3 = new FileOutputStream(fileName3);
    //how long in bytes is the file to read
    int fileLength = in.available();
    //the file length, file 2 and 3 should have
    int toWrite2, toWrite3;
    //the number of bytes to save in file 2 and 3 are file1 / 2
    toWrite2 = toWrite3 = fileLength / 2;
    //if filelength file1 is odd, then add 1 byte to file2 (that byte falls out due to division)
    if (fileLength % 2 != 0)
        toWrite2++;

    //define a byte array with file1 length
    byte[] data = new byte[fileLength];
    in.read(data, 0, fileLength);
    //write the data 0-toRead2 and toRead2-toRead3
    out2.write(data, 0, toWrite2);
    out3.write(data, toWrite2, toWrite3);

    out2.close();
    out3.close();

} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}