JBangを利用したサンプルプログラム(フォルダ内にある全てのファイルについてバイト数を表示)

PrintSize.java

///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS info.picocli:picocli:4.6.3
//JAVA 11+

import picocli.CommandLine;
import picocli.CommandLine.Command;
import picocli.CommandLine.Parameters;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.concurrent.Callable;
import java.util.stream.Stream;

@Command(name = "PrintSize", mixinStandardHelpOptions = true, version = "PrintSize 0.1",
        description = "Print file size")
class PrintSize implements Callable<Integer> {
    @Parameters(index = "0", description = "file path", defaultValue = ".")
    private Path path;

    @CommandLine.Option(names = {"-d", "--delimiter"}, defaultValue = "\t",
            description = "delimiter (default: \\t)")
    private String delimiter;

    public static void main(String... args) {
        int exitCode = new CommandLine(new PrintSize()).execute(args);
        System.exit(exitCode);
    }

    @Override
    public Integer call() {
        printFileSize(path.normalize().toAbsolutePath());
        return 0;
    }

    private void printFileSize(final Path path) {
        try {
            if (Files.isDirectory(path)) {
                printFolders(path);
            } else {
                System.out.printf("%s%s%d%n", path, delimiter, Files.size(path));
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private void printFolders(final Path path) throws IOException {
        try (Stream<Path> children = Files.list(path)) {
            children.forEachOrdered(this::printFileSize);
        }
    }
}