From 99e2b67e042c4b720eb38804524b5bc767337f41 Mon Sep 17 00:00:00 2001
From: drdev <drdev@cardforge.org>
Date: Wed, 15 Oct 2014 16:07:54 +0000
Subject: [PATCH] Prevent concurrent modification exception when moving token
 to a zone besides the graveyard

---
 .../src/main/java/forge/util/FCollection.java |  6 ++++
 .../main/java/forge/util/FCollectionView.java |  1 +
 .../src/main/java/forge/game/GameAction.java  | 34 ++++++++++++++-----
 3 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/forge-core/src/main/java/forge/util/FCollection.java b/forge-core/src/main/java/forge/util/FCollection.java
index 4ca1b95f9ef..bc73dc81bcf 100644
--- a/forge-core/src/main/java/forge/util/FCollection.java
+++ b/forge-core/src/main/java/forge/util/FCollection.java
@@ -251,4 +251,10 @@ public class FCollection<T> implements List<T>, Set<T>, FCollectionView<T>, Clon
         }
         return subList;
     }
+
+    @Override
+    public Iterable<T> threadSafeIterator() {
+        //create a new linked list for iterating to make it thread safe and avoid concurrent modification exceptions
+        return new LinkedList<T>(list);
+    }
 }
diff --git a/forge-core/src/main/java/forge/util/FCollectionView.java b/forge-core/src/main/java/forge/util/FCollectionView.java
index f877bfcd2c6..24515260300 100644
--- a/forge-core/src/main/java/forge/util/FCollectionView.java
+++ b/forge-core/src/main/java/forge/util/FCollectionView.java
@@ -13,4 +13,5 @@ public interface FCollectionView<T> extends Iterable<T> {
     int lastIndexOf(Object o);
     boolean contains(Object o);
     List<T> subList(int fromIndex, int toIndex);
+    Iterable<T> threadSafeIterator();
 }
\ No newline at end of file
diff --git a/forge-game/src/main/java/forge/game/GameAction.java b/forge-game/src/main/java/forge/game/GameAction.java
index 1abd0efc673..5d89886f955 100644
--- a/forge-game/src/main/java/forge/game/GameAction.java
+++ b/forge-game/src/main/java/forge/game/GameAction.java
@@ -675,23 +675,32 @@ public class GameAction {
                     if (zt == ZoneType.Battlefield) {
                         continue;
                     }
-                    for (Card c : p.getCardsIn(zt)) {
+                    Iterable<Card> cards = p.getCardsIn(zt).threadSafeIterator();
+                    for (Card c : cards) {
                         // If a token is in a zone other than the battlefield, it ceases to exist.
                         checkAgain |= stateBasedAction704_5d(c);
                     }
                 }
             }
-            List<Card> noRegCreats = new ArrayList<Card>();
-            List<Card> desCreats = new ArrayList<Card>();
-            for (Card c : game.getCardsIn(ZoneType.Battlefield)) {
+            Iterable<Card> cards = game.getCardsIn(ZoneType.Battlefield).threadSafeIterator();
+            List<Card> noRegCreats = null;
+            List<Card> desCreats = null;
+            for (Card c : cards) {
                 if (c.isCreature()) {
                     // Rule 704.5f - Put into grave (no regeneration) for toughness <= 0
                     if (c.getNetToughness() <= 0) {
+                        if (noRegCreats == null) {
+                            noRegCreats = new LinkedList<Card>();
+                        }
                         noRegCreats.add(c);
                         checkAgain = true;
-                    } else if (c.hasKeyword("CARDNAME can't be destroyed by lethal damage unless lethal damage dealt by a single source is marked on it.")) {
+                    }
+                    else if (c.hasKeyword("CARDNAME can't be destroyed by lethal damage unless lethal damage dealt by a single source is marked on it.")) {
                         for (final Integer dmg : c.getReceivedDamageFromThisTurn().values()) {
                             if (c.getNetToughness() <= dmg.intValue()) {
+                                if (desCreats == null) {
+                                    desCreats = new LinkedList<Card>();
+                                }
                                 desCreats.add(c);
                                 checkAgain = true;
                                 break;
@@ -700,6 +709,9 @@ public class GameAction {
                     }
                     // Rule 704.5g - Destroy due to lethal damage
                     else if (c.getNetToughness() <= c.getDamage()) {
+                        if (desCreats == null) {
+                            desCreats = new LinkedList<Card>();
+                        }
                         desCreats.add(c);
                         checkAgain = true;
                     }
@@ -721,11 +733,15 @@ public class GameAction {
                 }
             }
 
-            for (Card c : noRegCreats) {
-                sacrificeDestroy(c);
+            if (noRegCreats != null) {
+                for (Card c : noRegCreats) {
+                    sacrificeDestroy(c);
+                }
             }
-            for (Card c : desCreats) {
-                destroy(c, null);
+            if (desCreats != null) {
+                for (Card c : desCreats) {
+                    destroy(c, null);
+                }
             }
 
             if (game.getTriggerHandler().runWaitingTriggers()) {