import java.io.File;
import java.nio.file.Paths;
import java.util.stream.Stream;
public class Main {
public static void main(String[] args) {
final String dir = "C:\\data\\projects\\";
final String pattern = ".pdf";
final File file = Paths.get(dir).toFile();
Stream.of(file.list((pFile, pString) -> pString.endsWith(pattern)))
.forEach(System.out::println);;
}
}