### Question:
PointQuadTree { public void clear() { mChildren = null; if (mItems != null) { mItems.clear(); } } PointQuadTree(double minX, double maxX, double minY, double maxY);  PointQuadTree(Bounds bounds); private  PointQuadTree(double minX, double maxX, double minY, double maxY, int depth); private  PointQuadTree(Bounds bounds, int depth); void add(T item); boolean remove(T item); void clear(); Collection<T> search(Bounds searchBounds);  }### Answer:
@Test public void testClear() { mTree.add(new Item(.1, .1)); mTree.add(new Item(.2, .2)); mTree.add(new Item(.3, .3)); mTree.clear(); Assert.assertEquals(0, searchAll().size()); }