Java Reference
In-Depth Information
method can check if the square is an
X
or an
O
, while the
placeCharacter
method changes
the value of the square. Note that it is impossible that a square is both an
X
and an
O
at the
same time. Since the variables
isX
and
isO
are
private
, we can guarantee that at no point
both of them are set. The
clear
method simply resets the value of the rectangle, while the
hasValue
method returns
true
if the square is an
X
or an
O
, that is, it has a value.
Note that the
Square
class inherits from the
Rectangle2D.Double
class. Therefore, the
Square
class will have inside it a rectangular object (as a super object) and we can call
methods, such as
getX
,
getWidth
and so on, to retrieve the parameters of the rectangle.
As expected, the constructor of the
Square
class starts by calling the constructor of the
Rectangle2D.Double
class. This sets the top left corner and the width and height of the
rectangle.
Lastly, let us examine the
draw
method. The paintbrush (an object of type
Graphics2D
) and the possible images to be displayed are passed as parameters. The call
g2.draw(super.getBounds2D())
draws the surrounding rectangle. Next, the
drawImage
method is used to display the character
X
or the character
O
. Note that the
drawImage
method expects the coordinates of the rectangle as integers and therefore we need to cast
the coordinates of our rectangle to integers. Note as well that we have added one to the
second and third parameters in order for the image to not intersect the border. The fourth
and fifth parameters are the size of the image that will be displayed (can be different from
the size of the original image). In our case, we calculate the dimensions as the size of the
rectangle minus two in order to fit the image inside the surrounding rectangular frame.
Next, let us start examining the main class:
TicTacToe
. We will only override the
init
method from the
JApplet
class in it.
import
java .awt .
∗
;
import
java . net .
∗
;
import
java . util .
∗
;
import
javax . imageio .
∗
;
import
javax . swing .
∗
;
public class
TicTacToe
extends
JApplet
{
private
ArrayList
<
Square
>
squares =
new
ArrayList
<>
() ;
private
Image xImage , oImage ;
public void
initBoard()
{
squares =
new
ArrayList
<>
() ;
Dimension d = getSize () ;
double
dx = d.getWidth() / 3.0;
double
dy = d . getHeight () / 3 . 0 ;
for
(
int
x=0;x
{
for
(
int
y=0;y
<
3 ; y++)
<
3 ; x++)
{
squares .add(
new
Square(x
dx , y
dy , dx , dy) ) ;
∗
∗
}
repaint () ;
}
public void
init()
{
try
{
xImage = ImageIO. read (
new
URL(getCodeBase () ,
"images/x.jpg"
));
oImage = ImageIO. read(
new
URL(getCodeBase () ,
"images/o.jpg"
));
}
catch
(Exception exception)
{
initBoard() ;
