Java IO ObjectStreamField

Last Updated : 26 Oct, 2021

The Java. io. ObjectStreamField class is a description of a Serializable field from a Serializable interface. This class is serialization’s descriptor for classes. An array of The ObjectStreamFields is utilized to maintain the Serializable fields of a class. It includes the name and serialVersionUID of the class.

The Class Declaration for Java IO ObjectStreamField is as -

1. public class ObjectStreamField extends Object       // extends Keyword is used  

2. public class ObjectStreamField implements Comparable<Object>   // implements Keyword is used

Constructors of Java IO ObjectStreamField

Following Are The Two Constructors For The Class Java IO ObjectStreamField -

Sr. No.	Constructor	Description
1	ObjectStreamField (String name, Class<?> type)	This Constructor Creates a Serializable field with the specified type to it
2	ObjectStreamField (String name, Class<?> type, boolean unshared)	This Constructor Creates an ObjectStreamField representing a serializable field with the given name and type of it

Sr.

No.

Constructor

Description

ObjectStreamField (String name, Class<?> type)

This Constructor Creates a Serializable field with the specified type to it

ObjectStreamField (String name, Class<?> type, boolean unshared)

This Constructor Creates an ObjectStreamField representing a serializable field with the given name and type of it

Methods of Java IO ObjectStreamField

S.No.	Method	Method Type	Description
1	compareTo(Object obj)	int	This Method is Comparing this field with another ObjectStreamField
2	getName()	String	This method gives the name of the field
3	GetOffset()	int	This method returns the offset of the field within instance data
4	getType()	Class<?>	It gives the type of the field for the get type method
5	getTypeCode()	char	This method returns the character encoding of the field type
6	getTypeString()	String	This method returns the JVM type Signature
7	isPrimitive()	boolean	It returns true if the field has a primitive type
8	isUnshared()	boolean	It returns a boolean value indicating whether or not the serializable field represented by this ObjectStreamField instance is unshared.
9	setOffset( int offset)	protected void	This method returns offset within the instance of the data
10	toString()	String	It returns a string that describes all this field

Example:

Java

// Java program to illustrate the working
// of the Java IO ObjectStreamField class
import java.io.ObjectStreamClass;  
import java.util.Calendar;  
  
public class ObjectStreamClassExample
{  
     public static void main(String[] args)
     {  
             
          // creating a new object for the stream class for the Integers  
          ObjectStreamClass abc = ObjectStreamClass.lookup(String.class);  
  
          // getting the value field from ObjectStreamClass for the integers  
          System.out.println("" + abc.getField("value"));  
  
          // creating new object stream class for the  Calendar  
          ObjectStreamClass abc2 = ObjectStreamClass.lookup(Calendar.class);  
  
          // get the Class instance for abc2  
          System.out.println("" + abc2.getField("isTimeSet"));  
  
       }  
}

Output -

I value
Z isTimeSet

Example for Method of Java IO ObjectStreamField ( compareTo(Object obj) ) -

The subsequent illustration explains the usefulness of the java.io.ObjectStreamField.compareTo() method -

Java

// Java program to illustrate the working of the
// Java IO ObjectStreamField(compareTo(Object obj)) class
import java.io.*;

public class ObjectStreamField_ShowDemo {
   
   public static void main(String[] args) {
   
      // creating a new object stream class for The Integers
      ObjectStreamClass xyz = ObjectStreamClass.lookupAny(Integer.class);

      // getting the field value from Integer class
      ObjectStreamField field = xyz.getField("value");

      // creating a new object stream class for floats
      ObjectStreamClass xyz2 = ObjectStreamClass.lookupAny(Float.class);

      // getting the field value from Integer class
      ObjectStreamField field2 = xyz.getField("value");

      // comparing with another field
      System.out.println("" + field.compareTo(field2));
      
   }
}

Output :

Java.io.ObjectStreamClass in Java

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