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1.11 The Externalizable Interface

For Externalizable objects, only the identity of the class of the object is saved by the container; the class must save and restore the contents. The Externalizable interface is defined as follows:


public interface Externalizable extends Serializable
    public void writeExternal(ObjectOutput out)
        throws IOException;

    public void readExternal(ObjectInput in)
        throws IOException, java.lang.ClassNotFoundException;
The class of an Externalizable object must do the following:

Note - The writeExternal and readExternal methods are public and raise the risk that a client may be able to write or read information in the object other than by using its methods and fields. These methods must be used only when the information held by the object is not sensitive or when exposing it does not present a security risk.
An Externalizable class can optionally define the following methods:

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