Java Serializable EOF

Question

EDITED So I'm trying to save in a .ser file objects of type Product( containing name, quantity, price ) as it follows: each time I add a new product I add it in the file. Then, each time I launch a window, I want to read these products I previously saved, in a TreeSet by calling the following method in the window's constructor:

public void updateCurrentProducts()
{
        Product p=null;
        System.out.println("Updating the tree of products.");
         try
          {
             FileInputStream fileIn = new FileInputStream("products.ser");
             ObjectInputStream in = new ObjectInputStream(fileIn);
             int c;
            // if((c=in.read()) != -1)
             {
                // System.out.println("Not eof yet.");
                 while ((p = (Product) in.readObject()) != null)
                 {
                     addProduct(p);
                     System.out.println("Just found "+p.name+".");
                 }
             }
             in.close();
             fileIn.close();
          }catch(IOException ix)
          {
             ix.printStackTrace();
             return;
          } catch (ClassNotFoundException e) 
         {
            // TODO Auto-generated catch block
            e.printStackTrace();
         }
    }

This is how I add products:

public void addProduct(Product p)
    {
        System.out.println("Succesfully added new peoduct.");

         FileOutputStream fileOut;
        try 
        {
            fileOut = new FileOutputStream("products.ser");
            ObjectOutputStream out = new ObjectOutputStream(fileOut);
            out.writeObject(p);
            System.out.println("Just saved "+p.name);
            productTree.add(p);
             out.close();
             fileOut.close();
             System.out.printf("Serialized data is saved in products.ser");
        } 
        catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

However I get java.io.EOFException and I'm not sure why, since I have a condition not to access/save an elem unless ((p = (Product) in.readObject()) != null). I'm not sure how to avoid EOF. I tried with read() check, but it would simply avoid the problem, not help me save my changes. Also, I noticed only the last element I submit is saved. Any suggestions?

EDIT After implementing the suggestion, my error switched to java.io.StreamCorruptedException: invalid type code: AC.

I read this https://stackoverflow.com/a/2395269/4180889 but it's not clear for me what I should do if I want to keep the content.

score 2 · Answer 1 · answered Apr 14 '15 at 08:41

2

I noticed only the last element I submit is saved.

Its because the write operations is done on truncate mode.

fileOut = new FileOutputStream("products.ser");

Use true flag for append mode:

fileOut = new FileOutputStream("products.ser", true);

answered Apr 14 '15 at 08:41

I see the logic, however it must be a bigger problem since now it doesn't even save that last element. Or it doesn't read properly any elements. – Lorena Sfăt Apr 14 '15 at 08:46
_So to me it is perfectly clear, that you reopen the Stream and append more and more cheque objects. Which is not allowed. You have to write all cheque objects in 'one session'._ I'm confused. – Lorena Sfăt Apr 14 '15 at 08:54

Java Serializable EOF

1 Answers1