### Question:
StudyCharTableModel extends AbstractTableModel { @Override public Class<?> getColumnClass(int columnIndex) { if (columnIndex == 0) { return Study.class; } return EntityUtil.getConcreteTypeOrEntity(getCharacteristic(columnIndex).getValueType()); } StudyCharTableModel(StudyListPresentation pm, PresentationModelFactory pmf); int getColumnCount(); int getRowCount(); Object getValueAt(int rowIndex, int columnIndex); @Override String getColumnName(int columnIndex); @Override Class<?> getColumnClass(int columnIndex);  }### Answer:
@Test public void testGetColumnClass() { assertEquals(Study.class, d_model.getColumnClass(0)); assertEquals(Integer.class, d_model.getColumnClass(StudyCharacteristics.values().indexOf(BasicStudyCharacteristic.CENTERS) + 1)); assertEquals(Date.class, d_model.getColumnClass(StudyCharacteristics.values().indexOf(BasicStudyCharacteristic.STUDY_START) + 1)); }