Java可序列化的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.

Answer 1

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);

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