### Question:
VectorSeries extends ComparableObjectSeries { @Override public ComparableObjectItem remove(int index) { VectorDataItem result = (VectorDataItem) this.data.remove(index); fireSeriesChanged(); return result; } VectorSeries(Comparable key);  VectorSeries(Comparable key, boolean autoSort,
            boolean allowDuplicateXValues); void add(double x, double y, double deltaX, double deltaY); @Override ComparableObjectItem remove(int index); double getXValue(int index); double getYValue(int index); double getVectorXValue(int index); double getVectorYValue(int index); @Override ComparableObjectItem getDataItem(int index);  }### Answer:
@Test public void testRemove() { VectorSeries s1 = new VectorSeries("Series 1"); s1.add(1.0, 1.0, 1.0, 2.0); s1.add(3.0, 3.0, 3.0, 3.0); s1.add(2.0, 2.0, 2.0, 2.0); assertEquals(3, s1.getItemCount()); s1.remove(new XYCoordinate(2.0, 2.0)); assertEquals(3.0, s1.getXValue(1), EPSILON); s1.remove(new XYCoordinate(1.0, 1.0)); assertEquals(3.0, s1.getXValue(0), EPSILON); }