In Java 8 we can use Files.lines to read file into stream and do manipulations.
Let’s say we want to count the number of unique words in the file.

countries.txt

USA Canada
Germany England USA
Italy Germany

try (Stream lines =
    Files.lines(Paths.get("C:\\countries.txt"), Charset.defaultCharset())) {
  lines.flatMap(line -> Arrays.stream(line.split(" ")))
      .distinct().forEach(System.out::println);

} catch (IOException e) {
  e.printStackTrace();
}

//output
USA
Canada
Germany
England
Italy