simple-pathfinding/src/main/java/fr/uha/gasser/pathfinding/algorithm/AStarSearch.java

@@ -1,5 +1,7 @@
 package fr.uha.gasser.pathfinding.algorithm;
 
+import fr.uha.gasser.pathfinding.model.Grid;
+
 import java.awt.*;
 import java.util.*;
 import java.util.List;
@@ -8,10 +10,12 @@ class AStarSearch {
 
     private final Node start;
     private final Node goal;
+    private final Grid grid;
 
-    AStarSearch(Node start, Node goal) {
+    AStarSearch(Node start, Node goal, Grid grid) {
         this.start = start;
         this.goal = goal;
+        this.grid = grid;
     }
 
 
@@ -57,15 +61,22 @@ class AStarSearch {
     private List<Node> getNeighbors(Node current) {
         LinkedList<Node> neighbors = new LinkedList<>();
         for (Direction direction : Direction.values()) {
-            neighbors.add(getNeighbor(current, direction));
+            final Node neighbor = getNeighbor(current, direction);
+            // If neighbor is a wall or off the grid (null), don't add it to the list
+            if (neighbor != null) neighbors.add(neighbor);
         }
 
         return neighbors;
     }
 
     private Node getNeighbor(Node current, Direction direction) {
-        Node node = new Node(current);
-        node.setLoc(new Point(current.loc.x + direction.x, current.loc.y + direction.y));
+        final Dimension gridSize = grid.getSize();
+        final Node node = new Node(current);
+        final Point loc = new Point(current.loc.x + direction.x, current.loc.y + direction.y);
+        if (grid.get(loc).isWall()) return null;
+        // Don't overflow off the grid
+        if (loc.x > gridSize.width || loc.y > gridSize.height) return null;
+        node.setLoc(loc);
         return node;
     }
 

simple-pathfinding/src/main/java/fr/uha/gasser/pathfinding/algorithm/AStarWorker.java

@@ -1,12 +1,18 @@
 package fr.uha.gasser.pathfinding.algorithm;
 
 import fr.uha.gasser.pathfinding.model.Grid;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.swing.*;
 import java.awt.*;
+import java.util.Collections;
 import java.util.List;
 
 public class AStarWorker extends SwingWorker<List<Node>, List<Node>> {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(AStarWorker.class);
+
     private final Node start;
     private final Node goal;
     private final Grid target;
@@ -20,7 +26,7 @@ public class AStarWorker extends SwingWorker<List<Node>, List<Node>> {
 
     @Override
     protected List<Node> doInBackground() throws Exception {
-        AStarSearch aStar = new AStarSearch(start, goal);
+        AStarSearch aStar = new AStarSearch(start, goal, target);
         path = aStar.shortestPath();
         return path;
     }
@@ -28,6 +34,10 @@ public class AStarWorker extends SwingWorker<List<Node>, List<Node>> {
     @Override
     protected void done() {
         if (this.isCancelled()) return;
+        if (path.equals(Collections.EMPTY_LIST)) {
+            LOGGER.warn("There is no path between the nodes {} and {}.", start, goal);
+            return;
+        }
         path.forEach(node -> {
             if (! node.loc.equals(goal.loc)) target.setColor(node.loc, Color.BLUE);
         });

simple-pathfinding/src/main/java/fr/uha/gasser/pathfinding/model/Grid.java

@@ -49,6 +49,10 @@ public class Grid implements Iterable<Cell> {
         return new Cell(INVALID, null);
     }
 
+    public final Dimension getSize() {
+        return size;
+    }
+
     public void setColor(Point loc, Color color) {
         final Cell c = cells.get(loc.x + size.width * loc.y);
         final JLabel content = c.getContent();