simplify markFiringLines

src/RumbleBot.java

         int size = grid.length;
         for (int x = 0; x < size; x++) {
             for (int y = 0; y < size; y++) {
-
-                if (grid[x][y] == 'v') {
-                    int scanY = y;
-                    while (scanY < size && !obstacles.contains("" + grid[x][y])) {
-                        if (grid[x][scanY] == '.')
-                            grid[x][scanY] = '*';
-                        scanY++;
-                    }
-                }
-
-                if (grid[x][y] == '^') {
-                    int scanY = y;
-                    while (scanY >= 0 && !obstacles.contains("" + grid[x][y])) {
-                        if (grid[x][scanY] == '.')
-                            grid[x][scanY] = '*';
-                        scanY--;
-                    }
-                }
-
-                if (grid[x][y] == '>') {
-                    int scanX = x;
-                    while (scanX < size && !obstacles.contains("" + grid[x][y])) {
-                        if (grid[scanX][y] == '.')
-                            grid[scanX][y] = '*';
-                        scanX++;
-                    }
-                }
-
-                if (grid[x][y] == '<') {
-                    int scanX = x;
-                    while (scanX >= 0 && !obstacles.contains("" + grid[x][y])) {
-                        if (grid[scanX][y] == '.')
-                            grid[scanX][y] = '*';
-                        scanX--;
-                    }
+                switch (grid[x][y]) {
+                    case 'v' -> markLine(grid, x, y, 0, 1);
+                    case '^' -> markLine(grid, x, y, 0, -1);
+                    case '>' -> markLine(grid, x, y, 1, 0);
+                    case '<' -> markLine(grid, x, y, -1, 0);
                 }
+            }
+        }
+    }
 
+    private void markLine(char[][] grid, int x, int y, int dx, int dy) {
+        int size = grid.length;
+        x += dx;
+        y += dy;
+        while (x >= 0 && x < size && y >= 0 && y < size && !obstacles.contains("" + grid[x][y])) {
+            if (grid[x][y] == '.') {
+                grid[x][y] = '*';
             }
+            x += dx;
+            y += dy;
         }
     }
 
         int size = grid.length;
         int start = size / 2;
 
+        for (int y = 0; y < size; y++) {
+            for (char[] chars : grid) System.err.print(chars[y]);
+            System.err.println();
+        }
+
         boolean[][] visited = new boolean[size][size];
         Queue<Move> queue = new LinkedList<>();