Java.io.ObjectInputStream.readFields() Method

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Description

The java.io.ObjectInputStream.readFields() method reads the persistent fields from the stream and makes them available by name.

Declaration

Following is the declaration for java.io.ObjectInputStream.readFields() method

public ObjectInputStream.GetField readFields()

Parameters

  • NA

Return Value

google.gr

This method returns the GetField object representing the persistent fields of the object being deserialized

Exception

  • ClassNotFoundException -- if the class of a serialized object could not be found.

  • IOException -- If an I/O error has occurred.

  • NotActiveException -- if the stream is not currently reading objects.

Example

The following example shows the usage of java.io.ObjectInputStream.readFields() method.

package com.tutorialspoint;

import java.io.*;

public class ObjectInputStreamDemo {

   public static void main(String[] args) {

      try {

         // create a new file with an ObjectOutputStream
         FileOutputStream out = new FileOutputStream("test.txt");
         ObjectOutputStream oout = new ObjectOutputStream(out);

         // write something in the file
         oout.writeObject(new Example());
         oout.flush();

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

         // read the object and print the string
         Example a = (Example) ois.readObject();

         // print the string that is in Example class
         System.out.println("" + a.s);


      } catch (Exception ex) {
         ex.printStackTrace();
      }


   }

   static class Example implements Serializable {

      String s = "Hello World!";

      private String readObject(ObjectInputStream in)
              throws IOException, ClassNotFoundException {

         // call readFields in readObject
         ObjectInputStream.GetField gf = in.readFields();

         // save the string and return it
         return (String) gf.get("s", null);

      }
   }
}

Let us compile and run the above program, this will produce the following result:

Hello World!



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