How to write an Object to file in Java

Java object can write into a file for future access, this is called serialization. In order to do this, you have to implement the Serializableinterface, and use ObjectOutputStream to write the object into a file.

FileOutputStream fout = new FileOutputStream("c:\\address.ser");
ObjectOutputStream oos = new ObjectOutputStream(fout);
oos.writeObject(address);

1. Address.java

Create an “Address” object and implement Serializable interface. This object is going to write into a file.

package com.mkyong.io;
 
import java.io.Serializable;
 
public class Address implements Serializable{
 
	   String street;
	   String country;
 
	   public void setStreet(String street){
		   this.street = street;
	   }
 
	   public void setCountry(String country){
		   this.country = country;
	   }
 
	   public String getStreet(){
		   return this.street;
	   }
 
	   public String getCountry(){
		   return this.country;
	   }
 
	   @Override
	   public String toString() {
    	   return new StringBuffer(" Street : ")
    	   .append(this.street)
    	   .append(" Country : ")
    	   .append(this.country).toString();
	   }
 
}

2. Serializer.java

This class will write the “Address” object and it’s variable value (“wall street”, “united state”) into a file named “address.ser”, locate in c drive.

package com.mkyong.io;
 
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
 
public class Serializer {
 
   public static void main (String args[]) {
 
	   Serializer serializer = new Serializer();
	   serializer.serializeAddress("wall street", "united state");
   }
 
   public void serializeAddress(String street, String country){
 
	   Address address = new Address();
	   address.setStreet(street);
	   address.setCountry(country);
 
	   try{
 
		FileOutputStream fout = new FileOutputStream("c:\\address.ser");
		ObjectOutputStream oos = new ObjectOutputStream(fout);   
		oos.writeObject(address);
		oos.close();
		System.out.println("Done");
 
	   }catch(Exception ex){
		   ex.printStackTrace();
	   }
   }
}