2

I want to write an Object file with append. I have a class NewContact and main class below:

private String name;
    private String sex;
    private String mail;
    private String phone;
    private String image;
    //setter and getter method. removed it to avoid the long post.

    public NewContact() {
    }

    public NewContact(String name, String sex, String phone, String mail, String image) {
        this.name = name;
        this.sex = sex;
        this.mail = mail;
        this.phone = phone;
        this.image = image;

    }

    public String Xuat()
    {
        return this.getName()+" "+this.getSex()+" "+this.getPhone()+" "+this.getMail()+" "+this.getImage();

    }
    @Override
    public String toString(){
        //return this.name+" "+this.sex+" "+this.phone+" "+this.mail+" "+this.image;
        return this.getName()+" "+this.getSex()+" "+this.getPhone()+" "+this.getMail()+" "+this.getImage();
    }





///main class
    public static void main(String[] args) throws IOException, ClassNotFoundException {
            File file = new File("F:\\students.txt");
            ArrayList<NewContact> students = new ArrayList<NewContact>();
            students.add(new NewContact("Tom","Male","99245","f@gmail.com","sdgsg"));
            students.add(new NewContact("Mark","Male","365465","wegg@gmail.com","sdgsg"));
            students.add(new NewContact("Dave","Male","35346","dfhdfhfdh@gmail.com","sdgsg"));

            FileOutputStream fo = new FileOutputStream(file,true);
            ObjectOutputStream output = new ObjectOutputStream(fo);

            for ( NewContact s : students) {
                output.writeObject(s);
                //output.reset();

            }
            output.close();
            fo.close();

            FileInputStream is = new FileInputStream(file);
            ObjectInputStream input = new ObjectInputStream(is);

            try {
                while(true) {
                        NewContact s = (NewContact)input.readObject();
                        System.out.println(s);
                }
            } catch (EOFException ex) {

            }        
        }

I struggled with this issue for all day yesterday. Couldn't get to work. If I just write normal (no append), it's totally fine. But when I try to append it, it keep getting error StreamCorruptedException: invalid type code: AC.

During the research, I even added this class 

public class AppendingObjectOutputStream extends ObjectOutputStream{
    public AppendingObjectOutputStream(OutputStream out) throws IOException {
    super(out);
  }

  @Override
  protected void writeStreamHeader() throws IOException {
    // do not write a header, but reset:
    // this line added after another question
    // showed a problem with the original
    reset();
  }
}

STILL not work :(.

Quan Nguyen
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1 Answers1

0

ObjectOutputStream writes a stream header each time it is opened. But this header should appear only once, at the beginning of file. When you append to an existing file you should block writing this header, like this:

    ObjectOutputStream output = new ObjectOutputStream(fo) {
        @Override
        protected void writeStreamHeader() throws IOException {
        }
Evgeniy Dorofeev
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  • Specifically, the header is written when the stream is opened (for output). – Stephen C Apr 30 '16 at 06:30
  • I already tried that before, but not working :( – Quan Nguyen Apr 30 '16 at 09:04
  • @StephenC actually I did this before. even tried to add "reset();" in the writeStreamHeader method, but it no helping :(. – Quan Nguyen Apr 30 '16 at 09:18
  • @QuanNguyen You have to *not* do this the first time you write to the file: only when you are appending. But when you comment don't just wave your arms helplessly by saying "not working", "not helping", etc. State what actually happened. – user207421 May 31 '21 at 04:35