Never store reference to SQLiteDatabase

SQLiteDatabase closes automatically at random times. Storing a reference
to an open SQLiteDatabase eventually leads to a crash.
See: https://stackoverflow.com/questions/1483629/

app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteCheckmarkList.java

@@ -53,38 +53,27 @@ public class SQLiteCheckmarkList extends CheckmarkList
     @Nullable
     private CachedData cache;
 
-    @NonNull
-    private final SQLiteStatement invalidateStatement;
-
-    @NonNull
-    private final SQLiteStatement addStatement;
-
-    @NonNull
-    private final SQLiteDatabase db;
-
     public SQLiteCheckmarkList(Habit habit)
     {
         super(habit);
         sqlite = new SQLiteUtils<>(CheckmarkRecord.class);
-
-        db = Cache.openDatabase();
-        addStatement = db.compileStatement(ADD_QUERY);
-        invalidateStatement = db.compileStatement(INVALIDATE_QUERY);
     }
 
     @Override
     public void add(List<Checkmark> checkmarks)
     {
         check(habit.getId());
+        SQLiteDatabase db = Cache.openDatabase();
+        SQLiteStatement statement = db.compileStatement(ADD_QUERY);
         db.beginTransaction();
         try
         {
             for (Checkmark c : checkmarks)
             {
-                addStatement.bindLong(1, habit.getId());
-                addStatement.bindLong(2, c.getTimestamp());
-                addStatement.bindLong(3, c.getValue());
-                addStatement.execute();
+                statement.bindLong(1, habit.getId());
+                statement.bindLong(2, c.getTimestamp());
+                statement.bindLong(3, c.getValue());
+                statement.execute();
             }
 
             db.setTransactionSuccessful();
@@ -132,9 +121,11 @@ public class SQLiteCheckmarkList extends CheckmarkList
     public void invalidateNewerThan(long timestamp)
     {
         cache = null;
-        invalidateStatement.bindLong(1, habit.getId());
-        invalidateStatement.bindLong(2, timestamp);
-        invalidateStatement.execute();
+        SQLiteDatabase db = Cache.openDatabase();
+        SQLiteStatement statement = db.compileStatement(INVALIDATE_QUERY);
+        statement.bindLong(1, habit.getId());
+        statement.bindLong(2, timestamp);
+        statement.execute();
         observable.notifyListeners();
     }
 

app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteScoreList.java

@@ -49,14 +49,6 @@ public class SQLiteScoreList extends ScoreList
     @NonNull
     private final SQLiteUtils<ScoreRecord> sqlite;
 
-    @NonNull
-    private final SQLiteStatement invalidateStatement;
-
-    @NonNull
-    private final SQLiteStatement addStatement;
-
-    private final SQLiteDatabase db;
-
     @Nullable
     private CachedData cache = null;
 
@@ -69,25 +61,23 @@ public class SQLiteScoreList extends ScoreList
     {
         super(habit);
         sqlite = new SQLiteUtils<>(ScoreRecord.class);
-
-        db = Cache.openDatabase();
-        addStatement = db.compileStatement(ADD_QUERY);
-        invalidateStatement = db.compileStatement(INVALIDATE_QUERY);
     }
 
     @Override
     public void add(List<Score> scores)
     {
         check(habit.getId());
+        SQLiteDatabase db = Cache.openDatabase();
+        SQLiteStatement statement = db.compileStatement(ADD_QUERY);
         db.beginTransaction();
         try
         {
             for (Score s : scores)
             {
-                addStatement.bindLong(1, habit.getId());
-                addStatement.bindLong(2, s.getTimestamp());
-                addStatement.bindLong(3, s.getValue());
-                addStatement.execute();
+                statement.bindLong(1, habit.getId());
+                statement.bindLong(2, s.getTimestamp());
+                statement.bindLong(3, s.getValue());
+                statement.execute();
             }
 
             db.setTransactionSuccessful();
@@ -150,9 +140,11 @@ public class SQLiteScoreList extends ScoreList
     public synchronized void invalidateNewerThan(long timestamp)
     {
         cache = null;
-        invalidateStatement.bindLong(1, habit.getId());
-        invalidateStatement.bindLong(2, timestamp);
-        invalidateStatement.execute();
+        SQLiteDatabase db = Cache.openDatabase();
+        SQLiteStatement statement = db.compileStatement(INVALIDATE_QUERY);
+        statement.bindLong(1, habit.getId());
+        statement.bindLong(2, timestamp);
+        statement.execute();
         getObservable().notifyListeners();
     }
 

app/src/main/java/org/isoron/uhabits/models/sqlite/SQLiteStreakList.java

@@ -37,22 +37,19 @@ import java.util.*;
  */
 public class SQLiteStreakList extends StreakList
 {
+
+    private static final String INVALIDATE_QUERY =
+        "delete from Streak where habit = ? and end >= ?";
+
     private HabitRecord habitRecord;
 
     @NonNull
     private final SQLiteUtils<StreakRecord> sqlite;
 
-    private final SQLiteStatement invalidateStatement;
-
     public SQLiteStreakList(Habit habit)
     {
         super(habit);
         sqlite = new SQLiteUtils<>(StreakRecord.class);
-
-        SQLiteDatabase db = Cache.openDatabase();
-        String invalidateQuery = "delete from Streak where habit = ? " +
-                                 "and end >= ?";
-        invalidateStatement = db.compileStatement(invalidateQuery);
     }
 
     @Override
@@ -81,9 +78,11 @@ public class SQLiteStreakList extends StreakList
     @Override
     public void invalidateNewerThan(long timestamp)
     {
-        invalidateStatement.bindLong(1, habit.getId());
-        invalidateStatement.bindLong(2, timestamp - DateUtils.millisecondsInOneDay);
-        invalidateStatement.execute();
+        SQLiteDatabase db = Cache.openDatabase();
+        SQLiteStatement statement = db.compileStatement(INVALIDATE_QUERY);
+        statement.bindLong(1, habit.getId());
+        statement.bindLong(2, timestamp - DateUtils.millisecondsInOneDay);
+        statement.execute();
         observable.notifyListeners();
     }