Static fields ARE being serialized

Question

Hi there,
I wrote a small test class that serializes an object, writes the serialized object to file, read the serialized object from the file and then deserialize the object. The object being serialized contains normal fields, a transient field, and a few 4 static fields with varying access modifiers. For some reason the static variables ARE being serialized. From what I've read this should not happen, and for very good reasons.
Here is the object being serialized:
package serialization;
import java.io.Serializable;
import java.util.Formatter;
public class MySerializableObject implements Serializable {
     private static final long serialVersionUID = 1L;
     private int a = 1;
     private int b = 2;
     private transient int c = 3;
     static public int d = 4;
     static protected int e = 5;
     static private int f = 6;
     static int g = 7;
     @Override
     public String toString() {
          Formatter formatter = new Formatter();
          formatter.format("a=%1$s b=%2$s c=%3$s d=%4$s e=%5$s f=%6$s g=%7$s", a,b,c,d,e,f,g);
          return formatter.toString();
     public void setNewD(int newVal) {
          d = newVal;
}And here is the code that does the serialization:
package serialization;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class FileContentsObjectSerializer {
     File file;
     public FileContentsObjectSerializer(String name) {
          this.file = new File(name);
          if (this.file.exists()) {
               this.file.delete();
          try {
               this.file.createNewFile();
          } catch (IOException e) {
               e.printStackTrace();
     public void serialize(Object o) throws IOException {
          FileOutputStream fos = new FileOutputStream(this.file);
          ObjectOutputStream oos = new ObjectOutputStream(fos);
          oos.writeObject(o);
          oos.close();
          fos.close();
     public Object deserialize() throws IOException, ClassNotFoundException {
          FileInputStream fis = new FileInputStream(this.file);
          ObjectInputStream ois = new ObjectInputStream(fis);
          Object o = ois.readObject();
          fis.close();
          ois.close();
          return o;
     public static void main(String args[]) {
          MySerializableObject mso = new MySerializableObject();
          mso.setNewD(100);
          System.out.println("Object being serialized:"+mso.toString());
          FileContentsObjectSerializer ofs = new FileContentsObjectSerializer("c:/temptest.txt");
          try {
               ofs.serialize(mso);
               MySerializableObject result = (MySerializableObject) ofs.deserialize();
               System.out.println("Deserialized Object:    "+result.toString());
          } catch (Exception e) {
               e.printStackTrace();
}And here is the results I get:
Object being serialized:a=1 b=2 c=3 d=100 e=5 f=6 g=7
Deserialized Object:    a=1 b=2 c=0 d=100 e=5 f=6 g=7As you can see, both results are exactly the same, even though the setNewD value is not called on the deserialized object.
Any ideas?

Answer 1

You are misinterpreting the result. Try this main instead:
    public static void main(String args[]) {
        MySerializableObject mso = new MySerializableObject();
        mso.setNewD(100);
        System.out.println("Object being serialized:"+mso.toString());
        FileContentsObjectSerializer ofs = new FileContentsObjectSerializer("c:/temptest.txt");
        try {
            ofs.serialize(mso);
            mso.setNewD(-100); //a-oogah!
            MySerializableObject result = (MySerializableObject) ofs.deserialize();
            System.out.println("Deserialized Object:    "+result.toString());
        } catch (Exception e) {
            e.printStackTrace();
    }