package java.io;

import java.io.ObjectOutput;
import java.io.ObjectInput;

public interface Externalizable extends java.io.Serializable {
    /**
     * The object implements the writeExternal method to save its contents
     * by calling the methods of DataOutput for its primitive values or
     * calling the writeObject method of ObjectOutput for objects, strings
     * and arrays.
     * @exception IOException Includes any I/O exceptions that may occur
     * @since     JDK1.1
     */
    void writeExternal(ObjectOutput out) throws IOException;

    /**
     * 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.
     * @exception ClassNotFoundException If the class for an object being
     *              restored cannot be found.
     * @since     JDK1.1
     */
    void readExternal(ObjectInput in) throws IOException, ClassNotFoundException;
}

package java.io;

/**
 * Callback interface to allow validation of objects within a graph.
 * Allows an object to be called when a complete graph of objects has
 * been deserialized.
 */
public interface ObjectInputValidation {
    /**
     * Validates the object
     * @exception InvalidObjectException If the object cannot validate itself.
     * @since     JDK1.1
     */
    public void validateObject() throws InvalidObjectException;
}

package serialization;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.InvalidObjectException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectInputValidation;
import java.io.PrintWriter;

public class RecordedPerson 
    extends Person
    implements ObjectInputValidation
{
    // Constructor to create a recorded person and 
    // the associated record file
    public RecordedPerson(String name, int age, int id)
    {
        super(name, age);
        m_id = id;
        createRecordFile();
    }
    
    // Constructor to create a recorded person
    // and to open an already existing record file.
    public RecordedPerson(int id)
    {
        super(null, -1);
        m_id = id;
        setRecordFile();
        setBasicData();
    }
    
    // Reads the record from the record file
    // and returns it as a string.
    public String getRecord()
    {
        String data = "";
        BufferedReader in = null;
        try
        {
            in = new BufferedReader(
                         new FileReader(m_recordFile));
            while(true)
            {
                String line = in.readLine();
                if (line == null)
                    break;
                data += line + "\n";
            }
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (in != null)
            {
                try
                {
                    in.close();
                }
                catch(IOException e)
                {}
            }
        }
        return data;
    }
    
    // Adds a new item to the record file for this person
    public void addRecord(String item)
    {
        PrintWriter out = null;
        try
        {
            out = new PrintWriter(
                        new FileWriter(
                                m_recordFile.getAbsolutePath(),
                                true));
            out.println(item);
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (out != null)
                out.close();
        }
    }
    
    // Creates a new record file with name and age record
    // (If the record file already exists, assumes that it's valid)
    private void createRecordFile()
    {
        setRecordFile();
        if (!m_recordFile.exists())
        {
            // Create a new record file
            PrintWriter out = null;
            try
            {
                out = new PrintWriter(
                                new FileWriter(m_recordFile));
                out.println(getName() + "," + getAge());
            }
            catch(IOException e)
            {
                e.printStackTrace();
            }
            finally
            {
                if (out != null)
                    out.close();
            }
        }
        else
        {
            // Assume for simplicity that the name and age
            // actually correspond with the current ones.
        }
    }
    
    // Sets the record File object
    // If necessary, creates the subdirectory for record files.
    private void setRecordFile()
    {
        File records = new File("records");
        if (!records.exists())
            records.mkdir();    // Create directory
        m_recordFile = new File(records, "r" + m_id + ".rec");
    }
    
    // Reads the record file and extracts the name and age
    // and sets those values for the current recorded person.
    private void setBasicData()
    {
        // Extract the name and age from the record
        String record = getRecord();
        int commaIndex = record.indexOf(',');
        int eolIndex = record.indexOf('\n');
        String name = record.substring(0, commaIndex);
        String age = record.substring(commaIndex+1, eolIndex);
        // Set the name and age values
        setName(name);
        setAge(Integer.parseInt(age));
    }
    
    // Creates a string containing RecordedPerson information.
    public String toString()
    {
        String s = super.toString();
        s += ", ID=" + m_id + ", recordFile=" + m_recordFile;
        return s;
    }
    
    private void readObject(ObjectInputStream in)
        throws IOException,
                ClassNotFoundException
    {
        in.registerValidation(this, 0);
        in.defaultReadObject();
        // Ensure that the recordFile is properly set
        setRecordFile();
    }
    
    public void validateObject() 
        throws InvalidObjectException
    {
        if (getAge() > 40)
            throw new InvalidObjectException("No persons over 40 allowed");
    }
    
    //// Data ////
    private int   m_id;
    private transient File  m_recordFile;
}