### Question:
DefaultCategoryDataset extends AbstractDataset implements CategoryDataset, PublicCloneable, Serializable { @Override public Number getValue(int row, int column) { return this.data.getValue(row, column); } DefaultCategoryDataset(); @Override int getRowCount(); @Override int getColumnCount(); @Override Number getValue(int row, int column); @Override Comparable getRowKey(int row); @Override int getRowIndex(Comparable key); @Override List<Comparable> getRowKeys(); @Override Comparable getColumnKey(int column); @Override int getColumnIndex(Comparable key); @Override List<Comparable> getColumnKeys(); @Override Number getValue(Comparable rowKey, Comparable columnKey); void addValue(Number value, Comparable rowKey,
                         Comparable columnKey); void addValue(double value, Comparable rowKey,
                         Comparable columnKey); void setValue(Number value, Comparable rowKey,
                         Comparable columnKey); void setValue(double value, Comparable rowKey,
                         Comparable columnKey); void incrementValue(double value,
                               Comparable rowKey,
                               Comparable columnKey); void removeValue(Comparable rowKey, Comparable columnKey); void removeRow(int rowIndex); void removeRow(Comparable rowKey); void removeColumn(int columnIndex); void removeColumn(Comparable columnKey); void clear(); @Override boolean equals(Object obj); @Override int hashCode(); @Override Object clone();  }### Answer:
@Test public void testGetValue() { DefaultCategoryDataset d = new DefaultCategoryDataset(); d.addValue(1.0, "R1", "C1"); assertEquals(1.0, d.getValue("R1", "C1")); try { d.getValue("XX", "C1"); fail("UnknownKeyException should have been thrown on unknown key"); } catch (UnknownKeyException e) { assertEquals("Unrecognised rowKey: XX", e.getMessage()); } try { d.getValue("R1", "XX"); fail("UnknownKeyException should have been thrown on unknown key"); } catch (UnknownKeyException e) { assertEquals("Unrecognised columnKey: XX", e.getMessage()); } }
@Test public void testGetValue2() { DefaultCategoryDataset d = new DefaultCategoryDataset(); try { d.getValue(0, 0); fail("IndexOutOfBoundsException should have been thrown on getting key from empty set"); } catch (IndexOutOfBoundsException e) { assertEquals("Index: 0, Size: 0", e.getMessage()); } }