import java.io.*;

class Date implements Serializable
{
    public Date( )
    {
        this( 1, 1, 2000 );
    }
    
    public Date( int m, int d, int y )
    {
        month = m;
        date = d;
        year = y;
        
        if( !isValid( ) )  // really should throw exception...
        {
            month = date = 1; year = 2000;
        }
    }
    
    public String toString( )
    {
        return month + "/" + date + "/" + year;
    }
    
    // Not a real implementation
    private boolean isValid( )
    {
        return month >= 1 && month <= 12 && date >= 1 && date <= 31;
    }
    
    private void readObject( ObjectInputStream in )
      throws IOException, ClassNotFoundException
    {
        in.defaultReadObject( );
        if( !isValid( ) )
            throw new IOException( "Corrupted date" );
    }
    
    private int month;
    private int date;
    private int year;
}

class Person implements Serializable
{
    public static final long serialVersionUID = -2165050113482428735L;
    
    public Person( String n, Date b, Person m, Person f )
    {
        name = n;
        birthDate = b;
        mother = m;
        father = f;
    }
    
    public Person getFather( )
    {
        return father;
    }
    
    public Person getMother( )
    {
        return mother;
    }
    
    public String getName( )
    {
        return name;
    }
    
    public Date getBirthDate( )
    {
        return birthDate;
    }
    
    public String toString( )
    {
        return "[" + name + " born on=" + birthDate
                + "(mother=" + getMother( ).getName( )
                + ") (father=" + getFather( ).getName( ) + ")" + "]";
    }
    
    private void readObject( ObjectInputStream in ) 
        throws IOException, ClassNotFoundException
    {
        ObjectInputStream.GetField gf = in.readFields( );

        name = (String) gf.get( "name", null );
        birthDate = (Date) gf.get( "birthDate", null );
        
        Person [] parents = null;
        
        try 
        {
            parents = (Person[]) gf.get( "parents", null );
        }
        catch( IllegalArgumentException e )
        {
        }    
    
        if( parents != null )  // old format
        {
            mother = parents[ 0 ];
            father = parents[ 1 ];
        }
        else
        {
            mother = (Person) gf.get( "mother", null );
            father = (Person) gf.get( "father", null );
        }
  }
    
    public static final Person UNKNOWN = new Person( "????", new Date( ), null, null );
    
    private String name;
    private Date birthDate;
    private Person mother;
    private Person father;
}


class Example3
{
    
    public static void printPersons( Person [] arr )
    {
        for( int i = 0; i < arr.length; i++ )
            System.out.println( arr[ i ] );
    }
    
    public static void main( String[] args )
    {
        ObjectInputStream is = null;
        Person [] p = null;
        try
        {
            is = new ObjectInputStream( new FileInputStream( "ex3.ser" ) );
            p = (Person[]) is.readObject( );
            System.out.println( "****READING FROM ex3****" );
            printPersons( p );
            System.out.println( "Persons 0 and 4 same? "
                     + ( p[ 0 ] == p[ 4 ] ) );
            System.out.println( "Birthday 2 and 3 same? "
                     + ( p[ 2 ].getBirthDate( ) == p[ 3 ].getBirthDate( ) ) );
            is.close( );
        }
        catch( ClassNotFoundException e )
        {
            System.err.println( "What's a Person? " + e );
        }
        catch( IOException e )
        {
            System.err.println( "I/O problem: " + e );
        }
        finally
        {
            try
            {
                if( is != null )
                    is.close( );
            }
            catch( IOException e )
            {
                System.err.println( "Can't close: " + e ); 
            }
        }    
    
            // Write out to ex3a in new format
           ObjectOutputStream os = null;
        try
        {
            os = new ObjectOutputStream( new FileOutputStream( "ex3a.ser" ) );
            os.writeObject( p );
        }
        catch( IOException e )
        {
            System.err.println( "I/O problem: " + e );
            return;
        }
        finally
        {
            try
            {
                if( os != null )
                    os.close( );
            }   
            catch( IOException e )
            {
                System.err.println( "Can't close: " + e ); 
            } 
        }
        
        // Read back from ex3a
        try
        {
            is = new ObjectInputStream( new FileInputStream( "ex3a.ser" ) );
            Person [] people2 = (Person[]) is.readObject( );
            System.out.println( "****READING FROM ex3a****" );
            printPersons( people2 );
            System.out.println( "Persons 0 and 4 same? "
                     + ( people2[ 0 ] == people2[ 4 ] ) );
            System.out.println( "Birthday 2 and 3 same? "
                     + ( people2[ 2 ].getBirthDate( ) == people2[ 3 ].getBirthDate( ) ) );
            is.close( );
        }
        catch( ClassNotFoundException e )
        {
            System.err.println( "What's a Person? " + e );
        }
        catch( IOException e )
        {
            System.err.println( "I/O problem: " + e );
        }
        finally
        {
            try
            {
                if( is != null )
                    is.close( );
            }
            catch( IOException e )
            {
                System.err.println( "Can't close: " + e ); 
            }
        }  
    }        
}