Java - ObjectStreamClass getSerialVersionUID() method

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Description

The Java ObjectStreamClass getSerialVersionUID() method returns the serialVersionUID for this class. The serialVersionUID defines a set of classes all with the same name that have evolved from a common root class and agree to be serialized and deserialized using a common format. NonSerializable classes have a serialVersionUID of 0L.

• This method returns the serialVersionUID of a class.

• serialVersionUID is a unique identifier used during serialization to verify class compatibility.

• You call it on an ObjectStreamClass instance obtained via ObjectStreamClass.lookup(Class<?>).

Declaration

Following is the declaration for java.io.ObjectStreamClass.getSerialVersionUID() method.

public long getSerialVersionUID()

Parameters

NA

Return Value

This method returns the UUID of the class described by this descriptor.

Exception

NA

Example - Usage of ObjectStreamClass getSerialVersionUID() method

The following example shows the usage of ObjectStreamClass getSerialVersionUID() method.

ObjectStreamClassDemo.java

package com.tutorialspoint;

import java.io.ObjectStreamClass;
import java.util.Calendar;

public class ObjectStreamClassDemo {
   public static void main(String[] args) {
   
      // create a new object stream class for Integers
      ObjectStreamClass osc = ObjectStreamClass.lookup(Integer.class);

      // get the serial for Integers
      System.out.println("" + osc.getSerialVersionUID());

      // create a new object stream class for Calendar
      ObjectStreamClass osc2 = ObjectStreamClass.lookup(Calendar.class);

      // get the serial for Calendar
      System.out.println("" + osc2.getSerialVersionUID());
   }
}

Output

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

1360826667806852920
-1807547505821590642

Example - Get serialVersionUID of a user-defined serializable class

The following example shows the usage of ObjectStreamClass getSerialVersionUID() method. We're printing the UID of a User class that explicitly defines serialVersionUID.

ObjectStreamClassDemo.java

package com.tutorialspoint;

import java.io.ObjectStreamClass;
import java.io.Serializable;

public class ObjectStreamClassDemo {
   public static void main(String[] args) {
      ObjectStreamClass osc = ObjectStreamClass.lookup(User.class);
      System.out.println("serialVersionUID for User: " + osc.getSerialVersionUID());
   }

   static class User implements Serializable {
      private static final long serialVersionUID = 123456789L;
      String name;
      int age;
   }
}

Output

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

serialVersionUID for User: 123456789

Explanation

• The serialVersionUID is explicitly declared in the class.

• getSerialVersionUID() reflects that exact value.

• This is commonly used to enforce version compatibility across Java versions or systems.

Example - Get default serialVersionUID (auto-generated)

The following example shows the usage of ObjectStreamClass getSerialVersionUID() method. We're inspecting the serialVersionUID of a class without a declared UID.

ObjectStreamClassDemo.java

package com.tutorialspoint;

import java.io.ObjectStreamClass;
import java.io.Serializable;

public class ObjectStreamClassDemo {
   public static void main(String[] args) {
      ObjectStreamClass osc = ObjectStreamClass.lookup(Product.class);
      System.out.println("serialVersionUID for Product (auto-generated): " + osc.getSerialVersionUID());
   }

   static class Product implements Serializable {
      String name;
      double price;
   }
}

Output(Value will vary)

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

serialVersionUID for Product (auto-generated): -6562166864209567127

Explanation

• Since Product does not define a serialVersionUID, the JVM auto-generates one based on the class structure.

• That means if you modify the class (add/remove fields or methods), this value can change, breaking compatibility.