import com.liferay.petra.sql.dsl.DSLQueryFactoryUtil;
import com.liferay.petra.sql.dsl.query.DSLQuery;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import com.liferay.portal.kernel.model.UserTable;
import com.liferay.portal.kernel.service.UserLocalServiceUtil;

DSLQuery dslQuery = DSLQueryFactoryUtil.select(
        UserTable.INSTANCE.modifiedDate
).from(
        UserTable.INSTANCE
);
List<Date> rows = UserLocalServiceUtil.dslQuery(dslQuery);
DateFormat formatter = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

for (Date modifiedDate : rows) {
    out.println(formatter.format(modifiedDate));
    out.println("Class: " + modifiedDate.getClass().getName());
}