add Box.isEmpty()

Author: greenrobot

objectbox-java/src/main/java/io/objectbox/Box.java

@@ -294,6 +294,11 @@ public long count(long maxCount) {
         }
     }
 
+    /** Returns true if no objects are in this box. */
+    public boolean isEmpty() {
+        return count(1) == 0;
+    }
+
     @Temporary
     public List<T> find(Property property, String value) {
         Cursor<T> reader = getReader();
@@ -580,11 +585,6 @@ public void attach(T entity) {
         }
     }
 
-    // Sketching future API extension
-    private boolean isEmpty() {
-        return false;
-    }
-
     // Sketching future API extension
     private boolean isChanged(T entity) {
         return false;

tests/objectbox-java-test/src/test/java/io/objectbox/BoxTest.java

@@ -251,4 +251,20 @@ public void testGetId() {
         assertEquals(entity.getId(), box.getId(entity));
     }
 
+    @Test
+    public void testCountMaxAndIsEmpty() {
+        assertTrue(box.isEmpty());
+        putTestEntity("banana", 0);
+        assertFalse(box.isEmpty());
+
+        assertEquals(1, box.count(1));
+        assertEquals(1, box.count(2));
+        putTestEntity("apple", 0);
+        assertEquals(2, box.count(2));
+        assertEquals(2, box.count(3));
+
+        box.removeAll();
+        assertTrue(box.isEmpty());
+    }
+
 }