public void testCloning() {
        XYDataItem i1 = new XYDataItem(1.0, 1.1);
        XYDataItem i2 = null;
        try {
            i2 = (XYDataItem) i1.clone();
        }
        catch (CloneNotSupportedException e) {
            System.err.println("XYDataItemTests.testCloning: failed to clone.");
        }
        assertTrue(i1 != i2);
        assertTrue(i1.getClass() == i2.getClass());
        assertTrue(i1.equals(i2));