From b6501c9a29c42d98f3603f0217b6781a9d56f4ff Mon Sep 17 00:00:00 2001
From: Alinson Xavier <axavier@uwaterloo.ca>
Date: Tue, 30 May 2017 09:22:15 -0400
Subject: [PATCH] Fix NullPointerException

---
 .../main/java/org/isoron/uhabits/models/CheckmarkList.java    | 4 +++-
 .../org/isoron/uhabits/models/memory/MemoryCheckmarkList.java | 2 ++
 .../org/isoron/uhabits/models/sqlite/SQLiteCheckmarkList.java | 1 +
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/org/isoron/uhabits/models/CheckmarkList.java b/app/src/main/java/org/isoron/uhabits/models/CheckmarkList.java
index cf617628f..0556038fd 100644
--- a/app/src/main/java/org/isoron/uhabits/models/CheckmarkList.java
+++ b/app/src/main/java/org/isoron/uhabits/models/CheckmarkList.java
@@ -192,7 +192,7 @@ public abstract class CheckmarkList
         Checkmark newest = getNewestComputed();
         Checkmark oldest = getOldestComputed();
 
-        if (newest == null)
+        if (newest == null || oldest == null)
         {
             forceRecompute(from, to);
         }
@@ -208,6 +208,7 @@ public abstract class CheckmarkList
      *
      * @return oldest checkmark already computed
      */
+    @Nullable
     protected abstract Checkmark getOldestComputed();
 
     /**
@@ -285,5 +286,6 @@ public abstract class CheckmarkList
      *
      * @return newest checkmark already computed
      */
+    @Nullable
     protected abstract Checkmark getNewestComputed();
 }
diff --git a/app/src/main/java/org/isoron/uhabits/models/memory/MemoryCheckmarkList.java b/app/src/main/java/org/isoron/uhabits/models/memory/MemoryCheckmarkList.java
index 5b02be26a..9a566e51f 100644
--- a/app/src/main/java/org/isoron/uhabits/models/memory/MemoryCheckmarkList.java
+++ b/app/src/main/java/org/isoron/uhabits/models/memory/MemoryCheckmarkList.java
@@ -72,6 +72,7 @@ public class MemoryCheckmarkList extends CheckmarkList
     }
 
     @Override
+    @Nullable
     protected Checkmark getOldestComputed()
     {
         if(list.isEmpty()) return null;
@@ -79,6 +80,7 @@ public class MemoryCheckmarkList extends CheckmarkList
     }
 
     @Override
+    @Nullable
     protected Checkmark getNewestComputed()
     {
         if(list.isEmpty()) return null;
diff --git a/app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteCheckmarkList.java b/app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteCheckmarkList.java
index 42de31712..c63e1e1fd 100644
--- a/app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteCheckmarkList.java
+++ b/app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteCheckmarkList.java
@@ -153,6 +153,7 @@ public class SQLiteCheckmarkList extends CheckmarkList
     }
 
     @Override
+    @Nullable
     protected Checkmark getOldestComputed()
     {
         check(habit.getId());