Objects and Strings - A Concise and Practical Introduction to Programming Algorithms in Java - page 116

When an array of objects is built, all its elements Date[i] are initialized to
the null object. 1 Let us create a new kind of object for storing “events” that
are annotated dates, by defining the class XEvent as follows:

public class XEvent
{
Date when;
String what;

// Constructor
public XEvent(Date d, String text)
{
this.when=d;
this.what=text;
}
}

We can now write a static class function static XEvent oldest(XEvent[]
tab) attached to the class TestXEvent for seeking in an array and reporting
the oldest event as follows:

Program 5.7 The class XEvent and arrays of objects
class TestXEvent
{ static void Display (XEvent e )
{ System . out . print ( e . what+ ": " );

e.when.Display(); }

static boolean older (XEvent e1 , XEvent e2 )
{ return Date . isBefore (e1 .when , e2 .when) ; }

static XEvent o l d e s t (XEvent [ ] tab )

{ XEvent r e s u l t=tab [ 0 ] ;
for ( int i=1;i < tab . length;++i )
if (older(tab [ i ] , result )) result=tab [ i ];
return result ;

}

public static void main( String [ ] args )

{ Date d1= new Date(26 ,6 ,2003) ;
XEvent e1= new XEvent(d1 , "Birthday Julien" );
Date d2= new Date(20 ,11 ,2000) ;
XEvent e2= new XEvent(d2 , "Birthday Audrey" );
Date d3= new Date(23 ,6 ,1971) ;
XEvent e3= new XEvent(d3 , "Birthday Me" );
Display(e1) ;
XEvent [ ] tabEvent= new XEvent [ 3 ] ;
tabEvent [0]= e1 ;

1 This can be interpreted as the equivalent of the zero initialization of primitive
types.