Java ObjectInputStream defaultReadObject() Method

The defaultReadObject() method of ObjectInputStream class is used to read the non-static and non-transient fields of the current class from this stream, i.e, one cannot use defaultReadObject() to read the static fields. This may only be called from the readObject method of the class being desterilized. You cannot use defaultReadObject() directly.

Syntax

Parameter

No parameter is passed.

Returns

The return type is void.

Throws

NotActiveException , ClassNotFoundException , IOException.

Example 1

import java.io.*;
public class ObjectInputStreamdefaultreadobjectExample1 {
   public static void main(String[] args) {
      try {
           // create a new file with an ObjectOutputStream
         FileOutputStream outstream = new FileOutputStream("file1.txt");
         ObjectOutputStream objoutstream = new ObjectOutputStream(outstream);

         // write something in the file
         objoutstream.writeObject(new task());
         objoutstream.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream objinputstram = new ObjectInputStream(new FileInputStream("file1.txt"));

         // read the object and print the string
         task obj1 = (task) objinputstram.readObject();

         // print the string that is in task class
         System.out.println("string that is in task class : " + obj1.s);
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
   static class task implements Serializable {
      String s = "javaTpoint";
         // using defaultReadObject() with read() method
      private void readObject(ObjectInputStream in)
         throws IOException, ClassNotFoundException {
          // read the non static fields
         in.defaultReadObject();
      }
   }
}

Output:

string that is in task class : javaTpoint

Example 2

// file 1 and file 2 must be present in the same directory. 
import java.io.*;
public class ObjectInputStreamdefaultreadobjectExample2 {
   public static void main(String[] args) {
      try {
          // create a new file with an ObjectOutputStream
          FileOutputStream outstream = new FileOutputStream("file1.txt");
          ObjectOutputStream objoutstream = new ObjectOutputStream(outstream);
          FileInputStream instream = new FileInputStream("file2.txt"); 
          ObjectInputStream objinstream = new ObjectInputStream(instream);
          String str=objinstream.toString();
          // write something in the file
          objoutstream.writeObject(new task());
          objoutstream.writeObject(str);
          objoutstream.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream objinputstram = new ObjectInputStream(new FileInputStream("file1.txt"));
         // read and print an object and cast it as string
         System.out.println("" + (String) objinstream.readObject());

         // read the object and print the string
         task obj1 = (task) objinputstram.readObject();

         // print the string that is in task class
         System.out.println("string that is in task class  : " + obj1.s);
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
   static class task implements Serializable {
      String s = "javaTpoint";
        
// using defaultReadObject() with read() method
      private void readObject(ObjectInputStream in)
         throws IOException, ClassNotFoundException {
          // read the non static fields
         in.defaultReadObject();
      }
   }
}

Output:

java.io.ObjectInputStream@1b28cdfa
string that is in task class  : javaTpoint

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