@Test public void customColumnTypes() { GenericColumnId fileColumnId = new GenericColumnId("File", new ColumnType<>("File", GenericColumnId.class)); File fileA = new File("/path/to/a.txt"); File fileB = new File("/path/to/b.txt"); GenericColumn<File, GenericColumnId> fileColumn = GenericColumn.ofAll(fileColumnId, fileA, fileB); DataFrame df = DataFrame.of(fileColumn); assertEquals(2, df.getRowCount()); assertEquals(1, df.getColumnCount()); GenericColumn<File, GenericColumnId> column = df.getColumn(fileColumnId); assertEquals(fileColumn, column); File fileValue = df.getValueAt(1, fileColumnId); assertEquals(fileB, fileValue); }