### Question:
XYIntervalSeriesCollection extends AbstractIntervalXYDataset implements IntervalXYDataset, PublicCloneable, Serializable { @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof XYIntervalSeriesCollection)) { return false; } XYIntervalSeriesCollection that = (XYIntervalSeriesCollection) obj; return ObjectUtils.equal(this.data, that.data); } XYIntervalSeriesCollection(); void addSeries(XYIntervalSeries series); @Override int getSeriesCount(); XYIntervalSeries getSeries(int series); @Override Comparable getSeriesKey(int series); @Override int getItemCount(int series); @Override Number getX(int series, int item); @Override double getStartXValue(int series, int item); @Override double getEndXValue(int series, int item); @Override double getYValue(int series, int item); @Override double getStartYValue(int series, int item); @Override double getEndYValue(int series, int item); @Override Number getY(int series, int item); @Override Number getStartX(int series, int item); @Override Number getEndX(int series, int item); @Override Number getStartY(int series, int item); @Override Number getEndY(int series, int item); void removeSeries(int series); void removeSeries(XYIntervalSeries series); void removeAllSeries(); @Override boolean equals(Object obj); @Override Object clone();  }### Answer:
@Test public void testEquals() { XYIntervalSeriesCollection c1 = new XYIntervalSeriesCollection(); XYIntervalSeriesCollection c2 = new XYIntervalSeriesCollection(); assertEquals(c1, c2); XYIntervalSeries s1 = new XYIntervalSeries("Series"); s1.add(1.0, 1.1, 1.2, 1.3, 1.4, 1.5); c1.addSeries(s1); assertFalse(c1.equals(c2)); XYIntervalSeries s2 = new XYIntervalSeries("Series"); s2.add(1.0, 1.1, 1.2, 1.3, 1.4, 1.5); c2.addSeries(s2); assertEquals(c1, c2); c1.addSeries(new XYIntervalSeries("Empty Series")); assertFalse(c1.equals(c2)); c2.addSeries(new XYIntervalSeries("Empty Series")); assertEquals(c1, c2); }