Java Reference
In-Depth Information
} while (! board . isFree (startRow , startColumn , direction , size ) ) ;
board . populate (startRow , startColumn , direction , size , this );
} ...
The constants HORIZONTAL , VERTICAL ,and BOARD SIZE will be defined in the Board
class. Remember that constants are written in all capital letters. The first two constants
contain opposite Boolean values, while the third constant stores the size of the board (i.e.,
10 in our case). The isFree method of the Board class tests whether the ship can be placed
at the specified location. The populate method of the Board class places the ship on the
board. Note that the parameters of the ship and the this reference are sent as parameters
to the populate method of the Board class. The reason is that the Board class needs a
reference to the ship. It will give this reference to the cells of the board.
The constructor chooses a random start row, start column, and direction. Note that
we have two choices for the direction. Remember that Math.random() returns a random
number between 0 and 1. If this number is greater than 0.5, then we use the vertical
direction. Otherwise, we use the horizontal direction. The loop keeps executing until we are
able to successfully place the ship on the board (i.e., the isFree method returns true).
Next, we will introduce one more method to the Ship class. It is named isSunk and it
tests whether the ship is sunk (i.e., all its cells are visited).
public class Ship {
private int startRow , startColumn ;
private boolean direction ;
private int size ;
Board board ;
public boolean isSunk() {
if ( d i r e c t i o n == Bo a r d . VERTICAL) {
for ( int row = startRow , column = startColumn ;
row < = startRow + size 1 ;
if (!board. isVisited(row, column))
return false ;
else {
for ( int row = startRow , column = startColumn ;
= startColumn + size
1 ;
co lumn++)
if (!board. isVisited(row, column))
return false ;
return true ;
The isVisited method of the Board class will check if the cell in question is visited.
The above method goes through all cells of the ship. If one of the cells is not visited, then
the method returns false (i.e., the ship is not sunk). Otherwise, the method returns true .
Next, let us consider the Board class. In it, we will have the following constants.
public static final int BOARD SIZE = 10;
public static final boolean HORIZONTAL = true ;
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