Here is some sample code, provided you use Java 7:
@DataProvider
public Iterator<Object[]> testData()
throws IOException
{
final List<Object[]> list = new ArrayList<>();
for (final String line: Files.readAllLines(Paths.get("whatever"),
StandardCharsets.UTF_8)
list.add(new Object[]{ line, process(line) };
return list.iterator();
}
private static Whatever process(final String line)
{
// whatever
}