### Question:
NumberAxis extends ValueAxis implements Cloneable, Serializable { @Override public int hashCode() { return super.hashCode(); } NumberAxis();  NumberAxis(String label); RangeType getRangeType(); void setRangeType(RangeType rangeType); boolean getAutoRangeIncludesZero(); void setAutoRangeIncludesZero(boolean flag); boolean getAutoRangeStickyZero(); void setAutoRangeStickyZero(boolean flag); NumberTickUnit getTickUnit(); void setTickUnit(NumberTickUnit unit); void setTickUnit(NumberTickUnit unit, boolean notify,
                            boolean turnOffAutoSelect); NumberFormat getNumberFormatOverride(); void setNumberFormatOverride(NumberFormat formatter); MarkerAxisBand getMarkerBand(); void setMarkerBand(MarkerAxisBand band); @Override void configure(); @Override double valueToJava2D(double value, Rectangle2D area,
                                RectangleEdge edge); @Override double java2DToValue(double java2DValue, Rectangle2D area,
                                RectangleEdge edge); @Override AxisState draw(Graphics2D g2, double cursor, Rectangle2D plotArea,
            Rectangle2D dataArea, RectangleEdge edge,
            PlotRenderingInfo plotState); static TickUnitSource createStandardTickUnits(); static TickUnitSource createIntegerTickUnits(); static TickUnitSource createStandardTickUnits(Locale locale); static TickUnitSource createIntegerTickUnits(Locale locale); @Override List<ValueTick> refreshTicks(Graphics2D g2,
                             AxisState state,
                             Rectangle2D dataArea,
                             RectangleEdge edge); @Override Object clone(); @Override boolean equals(Object obj); @Override int hashCode(); static final boolean DEFAULT_AUTO_RANGE_INCLUDES_ZERO; static final boolean DEFAULT_AUTO_RANGE_STICKY_ZERO; static final NumberTickUnit DEFAULT_TICK_UNIT; static final boolean DEFAULT_VERTICAL_TICK_LABELS; }### Answer:
@Test public void testHashCode() { NumberAxis a1 = new NumberAxis("Test"); NumberAxis a2 = new NumberAxis("Test"); assertEquals(a1, a2); int h1 = a1.hashCode(); int h2 = a2.hashCode(); assertEquals(h1, h2); }