Box: add contains()

Author: greenrobot

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

@@ -317,6 +317,20 @@ public List<T> getAll() {
         }
     }
 
+    /**
+     * Check if an object with the given ID exists in the database.
+     * @since 2.7
+     * @return true if a object with the given ID was found, false otherwise
+     */
+    public boolean contains(long id) {
+        Cursor<T> reader = getReader();
+        try {
+            return reader.seek(id);
+        } finally {
+            releaseReader(reader);
+        }
+    }
+
     /**
      * Puts the given object in the box (aka persisting it). If this is a new entity (its ID property is 0), a new ID
      * will be assigned to the entity (and returned). If the entity was already put in the box before, it will be

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

@@ -79,9 +79,11 @@ public void testPutGetUpdateGetRemove() {
         assertEquals(value2, entityRead.getSimpleString());
 
         // and remove it
+        assertTrue(box.contains(id));
         assertTrue(box.remove(id));
         assertNull(box.get(id));
         assertFalse(box.remove(id));
+        assertFalse(box.contains(id));
     }
 
     @Test