Question

Create the ArrayList program example in listing 13.1, Battlepoint.

1. Describe the code (in your WORD document) in the 'if' statement
   • if (targets.indexOf(shot) > -1) {
2. ADD a NEW ArrayList of points called 'misses'
3. ADD code to add a point to the 'misses' list on a miss (if a SHOT does NOT hit a TARGET)
4. ADD code to place an 'M' in the final output map for all shots that were MISSES.
5. ADD code to place an H on the target for any shots that HIT a target.
6. SUBMIT your new Battlepoint code (no input arguments).

package com.java24hours;

import java.awt.*;
import java.util.*;
public class Battlepoint {
ArrayList<Point> targets = new ArrayList<Point>();
public Battlepoint() {
// create targets to shoot at
createTargets();
// display the game map
showMap();
// shoot at three points
shoot(7,4);
shoot(3,3);
shoot(9,2);
// display the map again
showMap();
}

private void showMap() {
System.out.println("\n 1 2 3 4 5 6 7 8 9");
for (int column = 1; column < 10; column++) {
for (int row = 1; row < 10; row++) {
if (row == 1) {
System.out.print(column + " ");
}
System.out.print(" ");
Point cell = new Point(row, column);
if (targets.indexOf(cell) > -1) {
// a target is at this position
System.out.print("X");
} else {
// no target is here
System.out.print(".");
}
System.out.print(" ");
}
System.out.println();
}
System.out.println();
}

private void createTargets() {
Point p1 = new Point(5,9);
targets.add(p1);
Point p2 = new Point(4,5);
targets.add(p2);
Point p3 = new Point(9,2);
targets.add(p3);
}

private void shoot(int x, int y) {
Point shot = new Point(x,y);
System.out.print("Firing at (" + x + "," + y + ") ... ");
if (targets.indexOf(shot) > -1) {
System.out.println("you sank my battlepoint!");
// delete the destroyed target
targets.remove(shot);
} else {
System.out.println("miss.");
}
}

public static void main(String[] arguments) {
new Battlepoint();
}
}

Answer 1

/************* BattlePoint.java ***************/

import java.awt.Point;
import java.util.ArrayList;

public class BattlePoint {
   ArrayList<Point> targets = new ArrayList<>();
   ArrayList<Point> misses = new ArrayList<>();
   Point hit = null;
   boolean after = false;

   public BattlePoint() {
       createTargets();
       showMap();
       shoot(7, 4);
       shoot(3, 3);
       shoot(9, 2);
       after = true;
       showMap();
   }

   private void showMap() {
       System.out.println("\n 1 2 3 4 5 6 7 8 9");
       for (int column = 1; column < 10; column++) {
           for (int row = 1; row < 10; row++) {
               if (row == 1) {
                   System.out.print(column + " ");
               }
               System.out.print(" ");
               Point cell = new Point(row, column);
               if (targets.indexOf(cell) > -1) {
                   System.out.print(String.format("%s", after ? "M" : "X"));
               } else if (after && hit != null && hit.x == row && hit.y == column) {
                   System.out.print("H");
               } else {
                   System.out.print(".");
               }
               System.out.print(" ");
           }
           System.out.println();
       }
       System.out.println();
   }

   private void createTargets() {
       Point p1 = new Point(5, 9);
       targets.add(p1);
       Point p2 = new Point(4, 5);
       targets.add(p2);
       Point p3 = new Point(9, 2);
       targets.add(p3);
   }

   private void shoot(int x, int y) {
       Point shot = new Point(x, y);
       System.out.print("Firing at (" + x + "," + y + ") ... ");
       if (targets.indexOf(shot) > -1) {
           System.out.println("you sank my battlepoint!");
           targets.remove(shot);
           hit = shot;
       } else {
           misses.add(shot);
           System.out.println("miss.");
       }
   }

   public static void main(String[] arguments) {
       new BattlePoint();
   }
}

/********** Output ***********/