StreamCorruptedException while de-serializing objects

Question

I have a class UserData that serializes objects,

import java.io.*;

public final class UserData implements Serializable
{
    private String name,username,password;
    private boolean male;
    private int age;

    public void setName(String name) { this.name = new String(name); }
    public void setUsername(String username) {this.username = new String(username); }
    public void setPassword(String password) {this.password = new String(password); }
    public void setAge(int age) { this.age = age; }
    public void setGender(boolean gender) { this.male = gender; }

    public String getName() { return new String(this.name); }
    public String getUsername() { return new String(this.username); }
    public String getPassword() { return new String(this.password); }
    public int getAge() { return this.age; }
    public boolean getGender() { return male; }

    public static void writeUserDataToFile(UserData data,String fileName)
    {
        try
        {
            if(data == null)
            {
                return;
            }
            ObjectOutputStream objOutput = new ObjectOutputStream(new FileOutputStream(new File(fileName),true));
            objOutput.writeObject(data);
            objOutput.flush();
            objOutput.close();
        }
        catch(FileNotFoundException ex)
        {
            System.out.println("Error : Cannot Save Data , The given filename \""+fileName+"\" is not valid.");
            return;
        }
        catch(NotSerializableException ex)
        {
            System.out.println("Error : It has been found that some data is not Serializable!");
            return;
        }
        catch(IOException ex)
        {
            System.out.println("Error : IOException has been encountered,");
            return;
        }
        catch(SecurityException S)
        {
            System.out.println("Error : Security Exception has been Encountered.");
            return;
        }
        catch(Exception e)
        {
            System.out.println("Error : Unknown Exception thrown!");
            return;
        }
        System.out.println("Sucess : Data written to \""+fileName+"\".");
    }
    public static UserData checkCredentials(String fileName,String userName,String passWord)
    {
        try
        {
            ObjectInputStream objInput = new ObjectInputStream(new FileInputStream(new File(fileName)));
            UserData data;
            while((data = (UserData)objInput.readObject())!=null)
            {
                if( userName.equals(data.getUsername()) && passWord.equals(data.getPassword()) )
                    return data;
            }
            objInput.close();
        }
        catch(Exception ex)
        {
            System.out.println("Error : Unknown Exception Caught while deserializing object.");
            ex.printStackTrace();
        }
        return null;
    }
}

To test this class , i wrote another class ,

public class TestUserData
{
    public static void main(String args[])
    {
        UserData data = new UserData();
        System.out.println("Serializing objects .... ");
        for(int i=0;i<5;i++)
        {
            data.setName("John");
            data.setAge(10+i);
            data.setGender((i%2==0)?true:false);
            data.setUsername("John"+i);
            data.setPassword(i+"John");
            UserData.writeUserDataToFile(data,"testSerial.dat");
        }
        System.out.println("de-Serializing objects .... ");
        for(int i=0;i<5;i++)
        {
            data = UserData.checkCredentials("testSerial.dat","John"+i,i+"John");
            if(data!=null)
            {
                System.out.println("Name : "+data.getName());
                System.out.println("Age  : "+data.getAge());
                System.out.println("Gender : "+(data.getGender() ? "Male" : "Female"));
            }
            else
            {
                System.out.println("Data for Object "+i+" not de-serialized.");
            }
        }
    }
}

Output i am getting

Serializing objects .... 
Sucess : Data written to "testSerial.dat".
Sucess : Data written to "testSerial.dat".
Sucess : Data written to "testSerial.dat".
Sucess : Data written to "testSerial.dat".
Sucess : Data written to "testSerial.dat".
de-Serializing objects .... 
Name : John
Age  : 10
Gender : Male
Error : Unknown Exception Caught while deserializing object.
java.io.StreamCorruptedException: invalid type code: AC
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1374)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
    at UserData.checkCredentials(UserData.java:67)
    at TestUserData.main(TestUserData.java:19)
Data for Object 1 not de-serialized.
Error : Unknown Exception Caught while deserializing object.
java.io.StreamCorruptedException: invalid type code: AC
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1374)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
    at UserData.checkCredentials(UserData.java:67)
    at TestUserData.main(TestUserData.java:19)
Data for Object 2 not de-serialized.
Error : Unknown Exception Caught while deserializing object.
java.io.StreamCorruptedException: invalid type code: AC
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1374)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
    at UserData.checkCredentials(UserData.java:67)
    at TestUserData.main(TestUserData.java:19)
Data for Object 3 not de-serialized.
Error : Unknown Exception Caught while deserializing object.
java.io.StreamCorruptedException: invalid type code: AC
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1374)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
    at UserData.checkCredentials(UserData.java:67)
    at TestUserData.main(TestUserData.java:19)
Data for Object 4 not de-serialized.

In the TestUserData class i am serializing 5 UserData objects, the serialization takes place well but during the de-serialization part , it is not able to deserialize past the first Object.

What should I change to make the program deserialize all the objects ??

score 1 · Accepted Answer · answered Jul 03 '13 at 10:13

1

You cannot append to the serialization file like that. There are headers that are written, so in your file you will have <header><data><header><data><header><data>...

The file needs to be of the form <header><data><data><data><data>

So while your reading method is correct, your saving method is actually wrong. You need to write all the objects that go into the same file at the same time.

answered Jul 03 '13 at 10:13

Kayaman

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But in my situation, i can't serialize all the objects at the same time, because the original purpose is using it in a application where users create their accounts at any time (i mean not at the same time) Any other alternatives other than serialization ?? – cyberpirate92 Jul 03 '13 at 10:16
With serialization, you would need to read the objects into memory, make required changes (such as add a user) then write them all back to the file. Another simple way would be to use a text file, with for example CSV format, having a single line for each user. A more robust solution would be to use a database (for example Java DB). – Kayaman Jul 03 '13 at 10:26
So i have to deserialize all the objects and then serialize them all again at the same time ? But wouldn't that increase the overhead ? – cyberpirate92 Jul 03 '13 at 10:31
1

Increase the overhead compared to what? You can't compare a working solution to a non-working solution. – user207421 Jul 04 '13 at 00:06

StreamCorruptedException while de-serializing objects

1 Answers1