t.addColumn("S1", String.class);
t.addColumn("S2", String.class);
t.addColumn("int1", int.class);
t.addColumn("int2", Integer[].class);
t.addColumn("float1", float.class);
t.addColumn("number1", Number.class);
t.addColumn("date1", Date.class);
t.addColumn("boolean1", boolean.class);
String[] stringColumns = TableUtilities.getValidStringColumnNamesInTable(t);
assertTrue(Arrays.asList(stringColumns).containsAll(Arrays.asList(new String[]{"S1", "S2"})));