Update Serializable Object

[Amit Bathla]

sir i want to know how to update object that i have written in file..
that is serialized object..
please help me sir
thanks
Amit

[Amit Bathla]

just tell me how to delete one or more objects from a file that i have written into file....
Amit

[karthikeyan Chockalingam]

I have provided a sample code to serialize and deserialize.

  import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
 
class Car implements Serializable {
 

private static final long serialVersionUID = 1L;
private String name;

public Car(String name){
this.name=name;
}

String getName(){
return this.name;
}
}
 
public class Test {
 
static final String fileName="a.txt";

public static void main(String[] args) throws Exception {

File file=new File(Test.fileName);

ObjectOutputStream oos=
new ObjectOutputStream(
new FileOutputStream(file));

oos.writeObject(new Car("Ferrari"));
oos.close();

//Later to deserialize 

ObjectInputStream ois=
new ObjectInputStream(
new FileInputStream(file));
Car ferrari=(Car)ois.readObject();

//To verify you deserialised the same print the name
System.out.println(ferrari.getName());

 
}
 
}  

[Amit Bathla]

that i know sir..
but how to delete or update an object from file???
Amit

[Garrett Rowe]

You'll have to explain a bit further what you're trying to do. Does your file conatain an array of objects, and you want to delete one. Or does your file contain just one object and you want to erase it. (Although it seem you could do that by just deleting the file).

[Keith Lynn]

If the objects are written sequentially to the file, the only way you're going to update it is to read all of the objects from the file into memory, and then write the updated objects to the file.