battleship/Ship.java

public class Ship{
   public static final int X = 0;
   public static final int Y = 1;
   private boolean vertical;
   private int[] start;
   private int[] end;
   private int length;
   public Ship(int[] start,int[] end){

      boolean vertical = start[Y] == end[Y];
      this.vertical = vertical;
      int cord;
      if (vertical) {
         cord = X;
      }
      else {
         cord = Y;
      }
      if (start[cord] < end[cord]){
         this.start = start;
         this.end = end;
      }
      else {
         this.start = end;
         this.end = start;
      }
      this.length = this.end[cord] - this.start[cord]+1;
   }

   public void print() {
      System.out.println("Start: " + "(" + this.start[X] + ", " + this.start[Y] + ")");
      System.out.println("End: " + "(" + this.end[X] + ", " + this.end[Y] + ")");
   }
   public int getLength() {
      return this.length;
   }
   public boolean isVertical() {
      return this.vertical;
   }
   public int[] getStart() {
      return this.start;
   }
   public int[] getEnd() {
      return this.end;
   }
   public boolean intersects(Ship other){
      boolean cond1;
      boolean cond2;
      boolean cond3;
      int cord1;
      int cord2;
      // <necessary bit, ensures algorithm works both when other is oriented horizontally or vertically>
      if (other.isVertical()) {
         cord1 = X;
         cord2 = Y;
      }
      else {
         cord1 = Y;
         cord2 = X;
      }
      // </necessary bit>

      int t_s1 = this.start[cord1];
      int t_e1 = this.end[cord1];
      int o_s1 = other.start[cord1];
      int o_e1 = other.end[cord1];
      
      int t_s2 = t_s2;
      int t_e2 = this.end[cord2];
      int o_s2 = other.start[cord2];
      int o_e2 = other.end[cord2];
      
      // lines are parallel
      if (this.vertical == other.isVertical()) {

         // overlaps
         cond1 = t_s2 == o_s2;

         // intersects
         cond2 = o_e1 <= t_s1;
         cond3 = t_e1 <= o_s1;
         
         return cond1 && (cond2 || cond3);
      }
      
      // lines are perpendicular
      else{

         // other in range of this with respect to axis cord1
         cond1 = (t_s1 >= o_s1) && (t_e1 <= o_e1);
         // this in range of other with respect to axis cord2
         cond2 = (o_s2 >= t_s2) && (o_e2 <= t_e2);
         return cond1 && cond2;
      }
   }
}