patch petit bug de modification concurente

src/pigeons/Bird.java

@@ -71,11 +71,14 @@ public class Bird implements Runnable {
   public Food findNearestFood() {
     Food nearestFood = null;
     int minDistance = Integer.MAX_VALUE;
-    for (Food f : park.getFoods()) {
+    int i = 0;
+    while(i < park.getFoods().size()){
+      Food f = park.getFoods().get(i);
       if (this.position.distance(f.getPosition()) < minDistance && f.isFresh()) {
         nearestFood = f;
         minDistance = this.position.distance(f.getPosition());
       }
+      i++;
     }
     return nearestFood;
   }

src/pigeons/Park.java

@@ -243,4 +243,8 @@ public class Park extends JPanel implements MouseListener {
     }
 
   }
+
+  public boolean isBusy(){
+    return (numWriter.get() > 0);
+  }
 }