Question

Looking at this method, it returns true if a given location contains a real ship that is still afloat. It says "real" ship because the 'emptySea' class extends Ship class with an inherited length of one, saving the need for null checks as empty locations now contain a non-null value meaning it does not contain a ship. 'isOccupied' will return true if that location contains a ship. The 'ships' array is used to determine which ship is in that location. 'allShips' is an ArrayList to which all ships were added too.

Given this information, I would like to understand how this method works - line by line. If someone could comment each line, that would be really helpful. Thank you.

public boolean shootAt(int row, int column) {
       int hit = 0;
       int sunkNum = 0;
       if (isOccupied(row, column) && !ships[row][column].isSunk()) {
           this.hitCount += 1;
           hit = 1;
       }
       this.shotsFired += 1;
       this.ships[row][column].shootAt(row, column);
       for (Ship ship: this.allShips) {
           if (ship.isSunk()){
               sunkNum += 1;
           }
       }
       this.shipsSunk = sunkNum;
       if (hit == 1) {
           return true;
       }
       return false;
   }

Answer 1

Note :- The comments for the code mentioned above is provided between multiple line comment /* */ along with the code

/*it is a method named shootAt which is of Boolean type i.e. this method will return value “True” or “False” . It is a public method i.e. it can be used anywhere in any class . This method takes the parameter row and column of integer datatype which tells the position of the ship*/

public boolean shootAt(int row, int column)

{
       int hit = 0; //variable hit of integer datatype initialized with value ‘0’.
       int sunkNum = 0; // variable sunkNum of integer datatype initialized with value ‘0’.

     /*In this If check there are two conditions mentioned as below , which if are true then the code in IF block will execute :-

1^st IF condition :- isOccupied(row, column) – the two parameters passed in the method shootAt are used in isOccupied() method to check if the ship is there or not . If isOccupied returns true then one condition in IF is satisfied else if it false then IF block is not executed as there is && between two conditions .

2^nd IF condition : !ships[row][column].isSunk() :- Sunk() is a method defined which is used here to find whether the parameters passed for the ship in method shootAt(int row, int column) has sunk or not .

If the ship has not sunk means the condtion is not true and is still on water floating then second IF condition is also satisfied .

       if (isOccupied(row, column) && !ships[row][column].isSunk())

     // Once the IF conditions are satisfied then the if block is executed

     {
           this.hitCount += 1; /* once the IF is satisfied that eans ship is still afloat and hitCount is incremented by 1*/
           hit = 1; // variable defined earlier is set to 1 which was earlier initialized to 0
       }

       this.shotsFired += 1;   /*method shootAt () also counts the shots fired at the ships . Therefore everytime shot is fired method shootAt () is executed , incrementing shotsFired by 1 each time .*/

       this.ships[row][column].shootAt(row, column); /* this is a self calling loop where shootAt() method is called again till the time it shows no ship exist*/

       for (Ship ship: this.allShips) /* for loop is started for all the ships to find how many have sunk */

      {
           if (ship.isSunk()) /* If the ship has sunk i.e. method isSunk() returns true then the IF block code is executed */

         {
               sunkNum += 1; /* if the ship has sunk then the variable sunkNum is incremented by to find the number of sunk ships*/
           }
       }
       this.shipsSunk = sunkNum; // assign the sunkNum value to shipsSunk method as parameter
       if (hit == 1) /*hit variable is set to 1 when the IF condition “if (isOccupied(row, column) && !ships[row][column].isSunk()) is true “ . Therefore if hit is equal to 1 then the method shootAt returns true else it returns false*/

    {
           return true;
       }
       return false;
   }