public abstract void readExternal (ObjectInput in) throws IOException, ClassNotFoundException

The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays. The readExternal method must read the values in the same sequence and with the same types as were written by writeExternal.

Parameters:
in    the stream to read data from in order to restore the object

Exceptions:
IOException    if I/O errors occur
ClassNotFoundException    If the class for an object being restored cannot be found.