### Question:
TimeTableXYDataset extends AbstractIntervalXYDataset implements Cloneable, PublicCloneable, IntervalXYDataset, DomainInfo,
                   TableXYDataset { public TimePeriod getTimePeriod(int item) { return (TimePeriod) this.values.getRowKey(item); } TimeTableXYDataset();  TimeTableXYDataset(TimeZone zone);  TimeTableXYDataset(TimeZone zone, Locale locale); boolean getDomainIsPointsInTime(); void setDomainIsPointsInTime(boolean flag); TimePeriodAnchor getXPosition(); void setXPosition(TimePeriodAnchor anchor); void add(TimePeriod period, double y, Comparable seriesName); void add(TimePeriod period, Number y, Comparable seriesName,
                    boolean notify); void remove(TimePeriod period, Comparable seriesName); void remove(TimePeriod period, Comparable seriesName,
            boolean notify); void clear(); TimePeriod getTimePeriod(int item); @Override int getItemCount(); @Override int getItemCount(int series); @Override int getSeriesCount(); @Override Comparable getSeriesKey(int series); @Override Number getX(int series, int item); @Override double getXValue(int series, int item); @Override Number getStartX(int series, int item); @Override double getStartXValue(int series, int item); @Override Number getEndX(int series, int item); @Override double getEndXValue(int series, int item); @Override Number getY(int series, int item); @Override Number getStartY(int series, int item); @Override Number getEndY(int series, int item); @Override double getDomainLowerBound(boolean includeInterval); @Override double getDomainUpperBound(boolean includeInterval); @Override Range getDomainBounds(boolean includeInterval); @Override boolean equals(Object obj); @Override Object clone();  }### Answer:
@Test public void testGetTimePeriod() { TimeTableXYDataset d = new TimeTableXYDataset(); d.add(new Year(1999), 1.0, "Series 1"); d.add(new Year(1998), 2.0, "Series 1"); d.add(new Year(1996), 3.0, "Series 1"); assertEquals(d.getTimePeriod(0), new Year(1996)); assertEquals(d.getTimePeriod(1), new Year(1998)); assertEquals(d.getTimePeriod(2), new Year(1999)); }