### Question:
SlidingCategoryDataset extends AbstractDataset implements CategoryDataset { @Override public int getRowIndex(Comparable key) { return this.underlying.getRowIndex(key); } SlidingCategoryDataset(CategoryDataset underlying, int firstColumn,
            int maxColumns); CategoryDataset getUnderlyingDataset(); int getFirstCategoryIndex(); void setFirstCategoryIndex(int first); int getMaximumCategoryCount(); void setMaximumCategoryCount(int max); @Override int getColumnIndex(Comparable key); @Override Comparable getColumnKey(int column); @Override List<Comparable> getColumnKeys(); @Override int getRowIndex(Comparable key); @Override Comparable getRowKey(int row); @Override List<Comparable> getRowKeys(); @Override Number getValue(Comparable rowKey, Comparable columnKey); @Override int getColumnCount(); @Override int getRowCount(); @Override Number getValue(int row, int column); @Override boolean equals(Object obj); @Override Object clone();  }### Answer:
@Test public void testGetRowIndex() { DefaultCategoryDataset underlying = new DefaultCategoryDataset(); underlying.addValue(1.0, "R1", "C1"); underlying.addValue(2.0, "R2", "C1"); underlying.addValue(3.0, "R3", "C1"); underlying.addValue(4.0, "R4", "C1"); SlidingCategoryDataset dataset = new SlidingCategoryDataset(underlying, 1, 2); assertEquals(0, dataset.getRowIndex("R1")); assertEquals(1, dataset.getRowIndex("R2")); assertEquals(2, dataset.getRowIndex("R3")); assertEquals(3, dataset.getRowIndex("R4")); }