Add ValueArray.getEmpty()

h2/src/main/org/h2/command/dml/SelectGroups.java

@@ -64,12 +64,6 @@ public abstract class SelectGroups {
          */
         private Iterator<Entry<ValueArray, Object[]>> cursor;
 
-        /**
-         * The key for the default group.
-         */
-        // Can be static, but TestClearReferences complains about it
-        private final ValueArray defaultGroup = ValueArray.get(new Value[0]);
-
         Grouped(Session session, ArrayList<Expression> expressions, int[] groupIndex) {
             super(session, expressions);
             this.groupIndex = groupIndex;
@@ -86,7 +80,7 @@ public abstract class SelectGroups {
         @Override
         public void nextSource() {
             if (groupIndex == null) {
-                currentGroupsKey = defaultGroup;
+                currentGroupsKey = ValueArray.getEmpty();
             } else {
                 Value[] keyValues = new Value[groupIndex.length];
                 // update group
@@ -120,7 +114,7 @@ public abstract class SelectGroups {
         public void done() {
             super.done();
             if (groupIndex == null && groupByData.size() == 0) {
-                groupByData.put(defaultGroup, createRow());
+                groupByData.put(ValueArray.getEmpty(), createRow());
             }
             cursor = groupByData.entrySet().iterator();
         }
@@ -185,10 +179,9 @@ public abstract class SelectGroups {
         @Override
         public ValueArray next() {
             if (cursor.hasNext()) {
-                Object[] values = cursor.next();
-                currentGroupByExprData = values;
+                currentGroupByExprData = cursor.next();
                 currentGroupRowId++;
-                return ValueArray.get(new Value[0]);
+                return ValueArray.getEmpty();
             }
             return null;
         }

h2/src/main/org/h2/expression/aggregate/AggregateDataHistogram.java

@@ -54,7 +54,7 @@ class AggregateDataHistogram extends AggregateData {
     @Override
     Value getValue(Database database, int dataType) {
         if (distinctValues == null) {
-            return ValueArray.get(new Value[0]).convertTo(dataType);
+            return ValueArray.getEmpty().convertTo(dataType);
         }
         ValueArray[] values = new ValueArray[distinctValues.size()];
         int i = 0;

h2/src/main/org/h2/value/ValueArray.java

@@ -20,6 +20,11 @@ import org.h2.util.StatementBuilder;
  */
 public class ValueArray extends Value {
 
+    /**
+     * Empty array.
+     */
+    private static final Object EMPTY = get(new Value[0]);
+
     private final Class<?> componentType;
     private final Value[] values;
     private int hash;
@@ -52,6 +57,15 @@ public class ValueArray extends Value {
         return new ValueArray(componentType, list);
     }
 
+    /**
+     * Returns empty array.
+     *
+     * @return empty array
+     */
+    public static ValueArray getEmpty() {
+        return (ValueArray) EMPTY;
+    }
+
     @Override
     public int hashCode() {
         if (hash != 0) {