ByteArraySpeichern

import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 

public class ByteArraySpeichern { 
    
    public static int[] ZufallsListe(int n){
        int[] liste = new int[n];
        int x;
        for(int i=0; i<n;i++){
            x = (int) Math.floor(n*Math.random()+1); 
            liste[i] = x;
        }

        return liste;
    }

    public static String convertToString(int[] liste) {
        int c;
        char m;
        StringBuilder ans = new StringBuilder();
        for(int i = 0;i<liste.length;i++){
            while (liste[i] > 0) {
                c = liste[i] % 10;
                liste[i] = liste[i] / 10;
                m = (char) ('0' + c);
                ans.append(m);
            }
            ans.append("|");
        }
        return ans.reverse().toString();
    }

    private boolean writeData(byte[] data, String fileName) { 
        File file = new File(fileName); 

        FileOutputStream fos = null; 
        try { 
            fos = new FileOutputStream(file); 
            fos.write(data); 
            fos.flush(); 
            return true; 
        } catch (FileNotFoundException e) { 
            System.err.println(file + " doesn't exist!"); 
        } catch (IOException e) { 
            System.err.println("Problems writing data to " + file); 
        } finally { 
            try { 
                if(fos != null) fos.close(); 
            }catch(IOException e){} 
        } 
        return false; 
    } 

    private byte[] readData(String fileName) { 
        File file = new File(fileName); 
        FileInputStream fis = null; 
        byte[] data = null; 
        try { 
            fis = new FileInputStream(file); 
            data = new byte[(int) file.length()]; 
            fis.read(data); 
        } catch (FileNotFoundException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } finally { 
            try { 
                if(fis != null) fis.close(); 
            } catch (IOException e) {} 
        } 
        return data; 
    } 

    public static void main(String[] args) { 
        int[] liste = ZufallsListe(25);
        String Array = convertToString(liste); 
        String fileName = "test"; 
        ByteArraySpeichern bas = new ByteArraySpeichern(); 
        if (bas.writeData(new String(Array).getBytes(), fileName)) 
            System.out.println("'" + Array 
                + "' erfolgreich als byte[] gespeichert"); 
        String ergebnis = new String(bas.readData(fileName)); 
        System.out.println("Aus Datei gelesen: '" + ergebnis + "'"); 
    } 
}