It depends on whether our object has implemented Serializable or Externalizable.
If Serializable has been implemented - constructor is not called during DeSerialization process.
But, if Externalizable has been implemented - constructor is called during DeSerialization process.
Full Program/SourceCode to show that If Serializable has been implemented - constructor is not called during DeSerialization process.
package SerDeser7SerConsCheck;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */
/*Author : AnkitMittal Copyright- contents must not be reproduced in any form*/
class Employee implements Serializable {
private static final long serialVersionUID = 1L;
private Integer id;
public Employee(){
System.out.println("No-arg constructor called");
}
public Employee(Integer id) {
System.out.println("1-arg constructor called");
this.id = id;
}
@Override
public String toString() {
return "Employee [id=" + id + "]";
}
}
public class SerializeConstructorCheck {
public static void main(String[] args) {
Employee object1 = new Employee(8);
try {
OutputStream fout = new FileOutputStream("ser.txt");
ObjectOutput oout = new ObjectOutputStream(fout);
System.out.println("Serialization process has started, serializing employee objects...");
oout.writeObject(object1);
fout.close();
oout.close();
System.out.println("Object Serialization completed.");
//DeSerialization process >
InputStream fin=new FileInputStream("ser.txt");
ObjectInput oin=new ObjectInputStream(fin);
System.out.println("\nDeSerialization process has started, displaying employee objects...");
Employee emp=(Employee)oin.readObject();
System.out.println(emp);
fin.close();
oin.close();
System.out.println("Object DeSerialization completed.");
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
}
}
/*OUTPUT
1-arg constructor called
Serialization process has started, serializing employee objects...
Object Serialization completed.
DeSerialization process has started, displaying employee objects...
Employee [id=8]
Object DeSerialization completed.
*/
|
If, we note output, constructor is not called during DeSerialization process.
Full Program/SourceCode to show that if Externalizable has been implemented - constructor is called during DeSerialization process.
>
package SerDeser7ExtConsCheck;
import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
/*Author : AnkitMittal Copyright- contents must not be reproduced in any form*/
class Employee implements Externalizable {
private static final long serialVersionUID = 1L;
private Integer id;
public Employee(){
System.out.println("No-arg constructor called");
}
public Employee(Integer id) {
System.out.println("1-arg constructor called");
this.id = id;
}
@Override
public String toString() {
return "Employee [id=" + id + "]";
}
/*
* define how Serialization process will write objects.
*/
@Override
public void writeExternal(ObjectOutput oo) throws IOException {
oo.writeInt(id);
}
/*
* define how deSerialization process will read objects.
*/
@Override
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
this.id=in.readInt();
}
}
public class ExternalizableConstructorCheck {
public static void main(String[] args) {
Employee object1 = new Employee(8);
try {
OutputStream fout = new FileOutputStream("ser.txt");
ObjectOutput oout = new ObjectOutputStream(fout);
System.out.println("Serialization process has started, serializing employee objects...");
oout.writeObject(object1);
fout.close();
oout.close();
System.out.println("Object Serialization completed.");
//DeSerialization process >
InputStream fin=new FileInputStream("ser.txt");
ObjectInput oin=new ObjectInputStream(fin);
System.out.println("\nDeSerialization process has started, displaying employee objects...");
Employee emp=(Employee)oin.readObject();
System.out.println(emp);
fin.close();
oin.close();
System.out.println("Object DeSerialization completed.");
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
}
}
/*OUTPUT
1-arg constructor called
Serialization process has started, serializing employee objects...
Object Serialization completed.
DeSerialization process has started, displaying employee objects...
No-arg constructor called
Employee [id=8]
Object DeSerialization completed.
*/
|
If, we note output, constructor is called during DeSerialization process.
RELATED LINKS>
serialVersionUID >
Constructor call during DeSerialization >