XStream - Object Streams

XStream provides alternative implementations of java.io.ObjectInputStream and java.io.ObjectOutputStream so that streams of objects can be serialized or de-serialized from XML. This is particularly useful when large sets of objects are to be processed, keeping one object in memory at a time.

Syntax: createObjectOutputStream()

ObjectOutputStream objectOutputStream = xstream.createObjectOutputStream(new FileOutputStream("test.txt"));

Syntax: createObjectInputStream()

ObjectInputStream objectInputStream = xstream.createObjectInputStream(new FileInputStream("test.txt"));

Let us now test the code with object streams in XStream.
Create a java class file named XStreamTester in C:\>XStream_WORKSPACE\com\tutorialspoint\xstream.
File: XStreamTester.java

package com.tutorialspoint.xstream;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.io.xml.StaxDriver;

public class XStreamTester {
   public static void main(String args[]){
   
      XStreamTester tester = new XStreamTester();
      XStream xstream = new XStream(new StaxDriver());
      
      xstream.autodetectAnnotations(true);
      
      Student student1 = new Student("Mahesh","Parashar");
      Student student2 = new Student("Suresh","Kalra");
      Student student3 = new Student("Ramesh","Kumar");
      Student student4 = new Student("Naresh","Sharma");
      
      try {
      
         ObjectOutputStream objectOutputStream = xstream.createObjectOutputStream(new FileOutputStream("test.txt"));
         
         objectOutputStream.writeObject(student1);
         objectOutputStream.writeObject(student2);
         objectOutputStream.writeObject(student3);
         objectOutputStream.writeObject(student4);
         objectOutputStream.writeObject("Hello World");
         
         objectOutputStream.close();
         
         ObjectInputStream objectInputStream = xstream.createObjectInputStream(new FileInputStream("test.txt"));
         
         Student student5 = (Student)objectInputStream.readObject();
         Student student6 = (Student)objectInputStream.readObject();
         Student student7 = (Student)objectInputStream.readObject();
         Student student8 = (Student)objectInputStream.readObject();
         
         String text = (String)objectInputStream.readObject();
         
         System.out.println(student5);
         System.out.println(student6);
         System.out.println(student7);
         System.out.println(student8);
         System.out.println(text);
      
      } catch (IOException e) {
         e.printStackTrace();
         
      } catch (ClassNotFoundException e) {
         e.printStackTrace();
      }
   }
}

@XStreamAlias("student")
class Student {

   private String firstName;
   private String lastName;
   
   public Student(String firstName, String lastName) {
      this.firstName = firstName;
      this.lastName = lastName;
   }

   public String getFirstName() {
      return firstName;
   }

   public String getLastName() {
      return lastName;
   }   

   public String toString(){
      return "Student [ firstName: "+firstName+", lastName: "+ lastName+ " ]";
   } 
}

Verify the Result
Compile the classes using javac compiler as follows:

C:\XStream_WORKSPACE\com\tutorialspoint\xstream>javac XStreamTester.java

Now run the XStreamTester to see the result:

C:\XStream_WORKSPACE\com\tutorialspoint\xstream>java XStreamTester

Verify the output as follows:

Student [ firstName: Mahesh, lastName: Parashar ]
Student [ firstName: Suresh, lastName: Kalra ]
Student [ firstName: Ramesh, lastName: Kumar ]
Student [ firstName: Naresh, lastName: Sharma ]
Hello World

Look at the content of the test.txt present at C:\>XStream_WORKSPACE\com\tutorialspoint\xstream folder.

<?xml version="1.0" ?>
<object-stream>
   <student>
      <firstName>Mahesh</firstName>
      <lastName>Parashar</lastName>
   </student>
   <student>
      <firstName>Suresh</firstName>
      <lastName>Kalra</lastName>
   </student>
   <student>
      <firstName>Ramesh</firstName>
      <lastName>Kumar</lastName>
   </student>
   <student>
      <firstName>Naresh</firstName>
      <lastName>Sharma</lastName>
   </student>
   <string>Hello World</string>
</object-stream>