### Question:
DateAxis extends ValueAxis implements Cloneable, Serializable { @Override public int hashCode() { return super.hashCode(); } DateAxis();  DateAxis(String label);  DateAxis(String label, TimeZone zone, Locale locale); TimeZone getTimeZone(); void setTimeZone(TimeZone zone); Locale getLocale(); void setLocale(Locale locale); Timeline getTimeline(); void setTimeline(Timeline timeline); DateTickUnit getTickUnit(); void setTickUnit(DateTickUnit unit); void setTickUnit(DateTickUnit unit, boolean notify,
                            boolean turnOffAutoSelection); DateFormat getDateFormatOverride(); void setDateFormatOverride(DateFormat formatter); @Override void setRange(Range range); @Override void setRange(Range range, boolean turnOffAutoRange,
                         boolean notify); void setRange(Date lower, Date upper); @Override void setRange(double lower, double upper); Date getMinimumDate(); void setMinimumDate(Date date); Date getMaximumDate(); void setMaximumDate(Date maximumDate); DateTickMarkPosition getTickMarkPosition(); void setTickMarkPosition(DateTickMarkPosition position); @Override void configure(); boolean isHiddenValue(long millis); @Override double valueToJava2D(double value, Rectangle2D area,
                                RectangleEdge edge); double dateToJava2D(Date date, Rectangle2D area,
                               RectangleEdge edge); @Override double java2DToValue(double java2DValue, Rectangle2D area,
                                RectangleEdge edge); Date calculateLowestVisibleTickValue(DateTickUnit unit); Date calculateHighestVisibleTickValue(DateTickUnit unit); static TickUnitSource createStandardDateTickUnits(); static TickUnitSource createStandardDateTickUnits(TimeZone zone,
            Locale locale); @Override List<ValueTick> refreshTicks(Graphics2D g2, AxisState state,
            Rectangle2D dataArea, RectangleEdge edge); @Override AxisState draw(Graphics2D g2, double cursor, Rectangle2D plotArea,
            Rectangle2D dataArea, RectangleEdge edge,
            PlotRenderingInfo plotState); @Override void zoomRange(double lowerPercent, double upperPercent); @Override boolean equals(Object obj); @Override int hashCode(); @Override Object clone(); static final DateRange DEFAULT_DATE_RANGE; static final double DEFAULT_AUTO_RANGE_MINIMUM_SIZE_IN_MILLISECONDS; static final Date DEFAULT_ANCHOR_DATE; }### Answer:
@Test public void testHashCode() { DateAxis a1 = new DateAxis("Test"); DateAxis a2 = new DateAxis("Test"); assertEquals(a1, a2); int h1 = a1.hashCode(); int h2 = a2.hashCode(); assertEquals(h1, h2); }