Hoge.java

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.Map.Entry;
import java.util.Map;
import java.util.stream.Stream;
import static java.util.Comparator.comparing;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.counting;

public class Hoge {
    public static void main(String[] args) throws IOException {
        final Map<String, Long> counts;
        try (final Stream<String> lines = Files.lines(Paths.get(args[0]))) {
            counts = lines.flatMap(line -> Arrays.stream(line.split("\\W+")))
                .filter(word -> !word.isEmpty())
                .collect(groupingBy(a -> a, counting()));
        }
        counts.entrySet()
            .stream().sorted(comparing(Entry::getValue))
            .map(it -> it.getValue() + ":" + it.getKey())
            .forEach(System.out::println);
    }
}