How to read serialized files?

Question

This in Java as well. I can't seem to get this method to work, the saving part works great and saves the object. But once I try to read the file it doesn't work and I get ObjectInputStream errors. I'm new to using the Serializable interface and none of the other questions seem to help me. The expected output is name Joe, weight 153, height 69. The errors are:

java.io.InvalidClassException: Person; local class incompatible: stream classdesc serialVersionUID = -1404541419531259795, local class serialVersionUID = 3020781085877336930 at java.io.ObjectStreamClass.initNonProxy(Unknown Source) at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source) at java.io.ObjectInputStream.readClassDesc(Unknown Source) at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.readObject(Unknown Source)

    public static boolean save(Person p, String filename) {
        try {
        ObjectOutputStream os = new ObjectOutputStream(
                new FileOutputStream(filename));
        os.writeObject(p);
        os.close();
        return true;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}

    public static Person read(String filename) {
    try {
        ObjectInputStream oi = new ObjectInputStream(new FileInputStream(
                filename));
        Object o = oi.readObject();
        oi.close();
        if (o instanceof Person)
            return (Person) o;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
    System.out.println("Do you want to save or load?");
    String option = s.next();
    Person p = new Person("Joe", 154, 69);
    if (option.equals("save")) {
        if (save(p, "newfile")) {
            System.out.println("Saved.");
        }
    }
    if (option.equals("load")) {
        Person p1 = read("newfile");
        if ((p1 != null)) {
            System.out.println(p1.getInfo());
        }
    }

}

}

You should tag it Java and mention it in your post. It will get better traction and attention. — Daved, Apr 15 '15 at 02:28
Where do the errors occur? I also notice you're not closing your stream. — Daved, Apr 15 '15 at 02:35
The errors occur at Object o = oi.readObject(); and Person p1 = read("newfile"); and yeah I just closed it now thanks — Krysiak, Apr 15 '15 at 02:44
Show the error, and show a compilable version of the code that includes the write side. You may be writing the file incorrectly. — vanza, Apr 15 '15 at 02:44
There we go, I'm pretty sure the writing part is fine but not 100 percent sure. — Krysiak, Apr 15 '15 at 02:58

score 1 · Accepted Answer · edited May 23 '17 at 12:28

1

Introduce serialVersionUID to the Person class as described in What is a serialVersionUID and why should I use it?

it seems that you have changed your Person class somehow, and now you can not read the saved version because the bytecode has been changed.

edited May 23 '17 at 12:28

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answered Apr 15 '15 at 03:08

jdevelop

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How to read serialized files?

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