I can't serialize and deserialize an object in Java

Question

I have a problem while serializing an object in Java(8). I saw many examples, but none of them work for me. The thing is that while serializing it doesn't serialize the object with its complete data. When I try to deserialize, it reads all the variables as null. I do this with Employee class. The code for Serialize.java :

public class Serialize {
private static ArrayList<Employee> emp = new ArrayList<Employee>();
public static void main(String[] args){
    try{

            emp.add(new Employee("Areg Hovhannisyan",5));
            emp.add(new Employee("Tigran Hakobyan",15));
            emp.add(new Employee("Shivanshu Ojha",11));
            FileOutputStream fos = new FileOutputStream("emps.emp");
            ObjectOutputStream out = new ObjectOutputStream(fos);
            out.writeObject(emp);

            out.close();
            fos.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
}
}

Employee.java:

import java.io.Serializable;
public class Employee implements Serializable {
private static int age;
private static String name;

public static int getAge() {
    return age;
}
public static void setAge(int age) {
    Employee.age = age;
}
public static String getName() {
    return name;
}
public static void setName(String name) {
    Employee.name = name;
}


public Employee(String name,int i) {
    this.name = name;
    this.age = i;
}
@Override
public String toString() {
    return "Name : " + getName() + ", Age : " + getAge();
}

}

Please give an example to do this,how to deserialize and please give it with a explanation because I also want to understand how it works.

What's your error? What did you try, to achieve some result? Please read this first: [How do I ask a good question?](http://stackoverflow.com/help/how-to-ask) — Nagy Vilmos, Mar 18 '15 at 12:50
and why age and name are static fields in your Employee class ? — Gerard Rozsavolgyi, Mar 18 '15 at 12:52
@GerardRozsavolgyi This is exactly OP's problem (and the reason why I asked for that class). — Seelenvirtuose, Mar 18 '15 at 13:03

score 2 · Answer 1 · answered Mar 18 '15 at 13:02

2

This is because your fields in class are static. Statics are implicitly transient and we can not serialize transient fields.

answered Mar 18 '15 at 13:02

Arpit Aggarwal

27,626
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Thank you, but could you suggest me a way to access the variables which I want to serialize in class Employee? If they are not static, I cannot access them from class Employee. I tried to use getters and setters but it didn't work. I tried to generate getters and setters with eclipse, but when I tried to use them, they weren't static. I applied the static modifier, but it gave an error. Couldn't access the variables also through "this." or "Employee." – Mar 20 '15 at 13:56

score 0 · Answer 2 · answered Mar 18 '15 at 13:21

0

The only problem in your code is that age and name fields should not be static for what you intend to do...

Your code should work just by removing the two static modifiers.

Then you maybe should read about static modifier to understand why your code couldn't work.

answered Mar 18 '15 at 13:21

Vinze

2,549
3
22
23

Thank you, but could you suggest me a way to access the variables which I want to serialize in class Employee? If they are not static, I cannot access them from class Employee. I tried to use getters and setters but it didn't work. I tried to generate getters and setters with eclipse, but when I tried to use them, they weren't static. I applied the static modifier, but it gave an error. Couldn't access the variables also through "this." or "Employee.". – Mar 20 '15 at 13:54
Once you have your array list try to iterate over it and print the toString of each instance... You'll see your code does not do what you expect it to do. The problem is that you should just not use `static` for what you want, and getters and setters shouldn't either. – Vinze Mar 20 '15 at 23:26
Ok, my mistake, got it, I will use modifier protected – Mar 22 '15 at 14:36

score 0 · Answer 3 · edited May 23 '17 at 12:06

0

Default serializable fields of a class are defined to be the non-transient and non-static fields.

Oracles Link

Here is stack OverFlow Link for it

edited May 23 '17 at 12:06

Community

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1

answered Mar 18 '15 at 13:40

rns

1,047
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score 0 · Answer 4 · answered Mar 18 '15 at 13:52

As mentioned in the above comments, Statics are implicitly transient. Also as per your code if the variables are static, you'll have one vaule(which is finally added) in your Arraylist. This is the behaviour of static variable.

Please give an example to do this,how to deserialize

Code with Deserialization:

public static void main(String[] args) throws IOException,
        ClassNotFoundException {
    FileOutputStream fos = null;
    ObjectOutputStream out = null;
    FileInputStream fis = null;
    ObjectInputStream in = null;
    try {

        emp.add(new Employee("Areg Hovhannisyan", 5));
        emp.add(new Employee("Tigran Hakobyan", 15));
        emp.add(new Employee("Shivanshu Ojha", 11));
        fos = new FileOutputStream("emps.emp");
        out = new ObjectOutputStream(fos);
        out.writeObject(emp);

        fis = new FileInputStream("emps.emp");
        in = new ObjectInputStream(fis);
        ArrayList<Employee> empRead = (ArrayList) in.readObject();
        System.out.println(empRead.get(0));
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        out.close();
        fos.close();
    }
}

I can't serialize and deserialize an object in Java

4 Answers4