[Chapter 11] ObjectInputValidation
Author: Mark Grand and Jonathan Knudsen
Date: Fri Aug 8 16:39:00 1997

#

| Chapter 11 The java.io Package |

# ObjectInputValidation

## Name

ObjectInputValidation

## Synopsis

Interface Name:

  `java.io.ObjectInputValidation`

Super-interface:

  None

Immediate Sub-interfaces:

  None

Implemented By:

  None

Availability:

  New as of JDK 1.1

## Description

The `ObjectInputValidation` interface defines a callback for object validation. A class implements this interface if it needs to validate deserialized objects. A class that needs to perform object validation on deserialized instances should pass a validation object to `ObjectInputStream.registerValidation()` at the beginning of its `private` `readObject()` method. When an object of that class is deserialized, the `validateObject()` method in the validation object is called. If the method is satisfied with the state of the deserialized object, it returns quietly; otherwise it should throw an `InvalidObjectException`.

The simplest case is to have a class do its own validation by implementing `ObjectInputValidation` itself and passing `this` to the `registerValidation()` method. For example, the following code fragment shows how to register for validation in `readObject()`. The `validateObject()` method always throws an exception:

    public class ValidateMe
        implements Serializable, ObjectInputValidation {
        private void readObject(ObjectInputStream in)
                     throws IOException, ClassNotFoundException {
            in.registerValidation(this, 0);
            in.defaultReadObject();
        }
        public void validateObject() throws InvalidObjectException {
            // if (this object is not valid)
                throw new InvalidObjectException("Object not valid!");
        }
    ...
    }

## Interface Declaration

    public abstract interface java.io.ObjectInputValidation {
      // Methods
      public abstract void validateObject();
    }

## Methods

### validateObject

#### public void validateObject() throws InvalidObjectException

Throws

  `InvalidObjectException`

    If the method is not satisfied with its state.

Description

  This method allows an object to check its own validity. An `InvalidObjectException` should be thrown if anything is invalid.

## See Also

`ObjectInput`, `ObjectInputStream`

ObjectInputStream |  | ObjectOutput