Подкиньте идею для решения задачи

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 
        String file1 = reader.readLine();
        String file2 = reader.readLine();
 
        BufferedInputStream stream1 = new BufferedInputStream(new FileInputStream(file1));
        DataOutputStream stream2 = new DataOutputStream((new FileOutputStream(file2)));
 
        byte[] numbers = new byte[stream1.available()];
        stream1.read(numbers);
        stream1.close();
 
        String value = new String(numbers);
        for (String s : value.split(" ")) {
            long x = Math.round(Double.valueOf(s));
            stream2.writeBytes(Long.toString(x)+" ");
        }
        stream2.close();
    }
}

Scanner scan = new Scanner(new File ("test.txt"));
while(scan.hasNextDouble){
double x = scan.nextDouble();
...
}

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
 
import static java.nio.file.StandardOpenOption.APPEND;
import static java.nio.file.StandardOpenOption.CREATE;
import static java.nio.file.StandardOpenOption.WRITE;
 
public class RoundExample {
    public static void main(String[] args) throws IOException {
        Files.write(Paths.get("output.txt"),
                Files.readAllLines(Paths.get("input.txt")).stream().flatMap((Function<String, Stream<String>>) line ->
                        Arrays.stream(line.split("\\s+")).parallel().map(value -> String.valueOf(Math.round(Double.valueOf(value))))).collect
                        (Collectors.toList()), CREATE, WRITE, APPEND);
    }
}

public class RoundExample {
    public static void main(String[] args) throws IOException {
        Files.write(
                Paths.get("output.txt"),
                Files.readAllLines(Paths.get("input.txt")).stream().flatMap(line ->
                        Arrays.stream(line.split("\\s+")).parallel().map(value -> String.valueOf(Math.round(Double.valueOf(value))))).collect
                        (Collectors.joining(" ")).getBytes(),
                CREATE, WRITE, APPEND
        );
    }
}