Files in Directory Compare with FileList

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Set;
import java.util.TreeSet;
import java.util.stream.Collectors;

public class CheckFile {
    public static void main(String[] args) {
        hasTwoArgs(args);
        Path targetFolder = Paths.get(args[0]);
        isDirectory(targetFolder);
        Set<Path> targetChildren = children(targetFolder);
        Path fileList = Paths.get(args[1]);
        isReadable(fileList);
        Set<Path> listed = read(fileList);
        format(targetChildren, listed);
    }

    private static Set<Path> children(Path target) {
        Set<Path> ret = new TreeSet<>();
        Path current = Paths.get(".").toAbsolutePath();
        try {
            for (Path p: Files.list(target).collect(Collectors.toList())) {
                if (Files.isRegularFile(p)) {
                    ret.add(current.relativize(p.toAbsolutePath()).toAbsolutePath());
                    continue;
                }
            }
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(1);
        }
        return ret;
    }

    private static void format(Set<Path> target, Set<Path> list) {
        Path current = Paths.get(".").toAbsolutePath();
        for (Path p: target) {
            if (list.contains(p)) {
                System.out.print("○ ");
            } else {
                System.out.print("× ");
            }
            System.out.println(current.relativize(p.toAbsolutePath()));
        }
    }

    private static void hasTwoArgs(String[] args) {
        if (args.length != 2) {
            usage();
        }
    }

    private static void isDirectory(Path target) {
        if (Files.isDirectory(target)) {
            return;
        }
        usage();
    }

    private static void isReadable(Path path) {
        if (Files.isReadable(path)) {
            return;
        }
        usage();
    }

    private static Set<Path> read(Path path) {
        Set<Path> ret = new TreeSet<>();
        try {
            for (String s: Files.readAllLines(path)) {
                ret.add(Paths.get(s).toAbsolutePath());
            }
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(1);
        }
        return ret;
    }

    private static void usage() {
        System.err.println("ERROR: usage: java " + CheckFile.class.getName() + " folder filelist");
        System.exit(1);
    }
}