Java Reference
In-Depth Information
Next, an integer array called holiday is created. This array holds the number of each
work holiday in the year 2007, beginning with 1 (New Year's Day) and ending with 359
(Christmas).
The holiday array is used to add each holiday to the sked bit set. A for loop iterates
through the holiday array and calls the method addHoliday( int ) with each one (lines
10-12).
The addHoliday( int ) method is defined in lines 15-17. The argument represents the
day that should be added. The bit set's set( int ) method is called to set the bit at the
specified position to 1 . For example, if set( 359 ) was called, the bit at position 359
would be given the value 1 .
The HolidaySked class also has the ability to determine whether a specified day is a hol-
iday. This is handled by the isHoliday( int ) method (lines 19-22). The method calls the
bit set's get( int ) method, which returns true if the specified position has the value 1
and false otherwise.
This class can be run as an application because of the main() method (lines 24-40). The
application takes a single command-line argument: a number from 1 to 365 that repre-
sents one of the days of the year. The application displays whether that day is a holiday
according to the schedule of the HolidaySked class. Test the program with values such as
15 (Martin Luther King Day) or 103 (my 40th birthday). The application should respond
that day 15 is a holiday but day 103, sadly, is not.
Vectors
Perhaps the most popular of the data structures described today, the Vector class imple-
ments a vector , an expandable and contractible array of objects. Because the Vector
class is responsible for changing size as necessary, it has to decide when and how much
to grow or shrink as elements are added and removed. You can easily control this aspect
of vectors upon creation.
Before getting into that, take a look at how to create a basic vector:
Vector v = new Vector();
This constructor creates a default vector containing no elements. All vectors are empty
upon creation. One of the attributes that determines how a vector sizes itself is its initial
capacity, or the number of elements it allocates memory for by default.
The size of a vector is the number of elements currently stored in it.
The capacity of a vector is the amount of memory allocated to hold elements, and it is
always greater than or equal to the size.
Search WWH ::




Custom Search