NumberEditorExt extends DefaultCellEditor { @Override public boolean stopCellEditing() { if (!isValid()) return false; return super.stopCellEditing(); } NumberEditorExt();  NumberEditorExt(NumberFormat format);  NumberEditorExt(boolean useStrictFormatter);  NumberEditorExt(NumberFormat format, boolean useStrictFormatter); @Override boolean stopCellEditing(); @Override Component getTableCellEditorComponent(JTable table, Object value,
                                             boolean isSelected,
                                             int row, int column); @Override Number getCellEditorValue(); @Override JFormattedTextField getComponent();  }
@Test public void testEditorStrictNullValue() { table.getColumn(INTEGER_COLUMN).setCellEditor(cellEditorStrict); table.editCellAt(0, INTEGER_COLUMN); cellEditorStrict.stopCellEditing(); }