Nggarap file ing Jawa

1. Fileskelas

Kanggo nggarap file, ana kelas sarana sing apik - java.nio.file.Files. Wis cara kanggo saben kesempatan. Kabeh cara saka kelas iki statis lan operate ing obyek Path. Ana akeh cara, mula kita bakal nimbang mung sing paling penting:

Path createFile(Path path)

Path createDirectory(Path path)

Path createDirectories(Path path)

Path createTempFile(prefix, suffix)

Path createTempDirectory(prefix)

void delete(Path path)

Path copy(Path src, Path dest)

Path move(Path src, Path dest)

boolean isDirectory(Path path)

boolean isRegularFile(Path path)

boolean exists(Path path)

long size(Path path)

byte[] readAllBytes(Path path)

String readString(Path path)

List<String> readAllLines(Path path)

Path write(Path path, byte[])

Path writeString(Path path, String str)

DirectoryStream<Path> newDirectoryStream(Path dir)

2. Nggawe file lan direktori

File lan direktori gampang banget digawe. Ayo yakin karo sawetara conto:

Files.createFile(Path.of("c:\\readme.txt"));

Files.createDirectory(Path.of("c:\\test"));

Files.createDirectories(Path.of("c:\\test\\1\\2\\3"));

3. Nyalin, mindhah lan mbusak

Nyalin, mindhah lan mbusak file kaya gampang. Iki uga ditrapake kanggo direktori, nanging kudu kosong.

Path path1 = Path.of("c:\\readme.txt");
Path path2 = Path.of("c:\\readme-copy.txt");
Files.copy(path1, path2);

Path path1 = Path.of("c:\\readme.txt");
Path path2 = Path.of("d:\\readme-new.txt");
Files.move(path1, path2);

Path path = Path.of("d:\\readme-new.txt");
Files.delete(path);

4. Priksa jinis file lan orane

Yen sampeyan duwe path sing diwenehake dening wong liya, sampeyan pengin ngerti apa iku file utawa direktori. Lan umume, apa file / direktori kasebut ana utawa ora?

Ana cara khusus kanggo iki uga. Sampeyan uga bisa ngerteni dawa file kanthi gampang:

Files.isRegularFile(Path.of("c:\\readme.txt"));

true

Files.isDirectory(Path.of("c:\\test"));

true

 Files.exists(Path.of("c:\\test\\1\\2\\3"));

false

Files.size(Path.of("c:\\readme.txt"));

10112

5. Nggarap isi file

Pungkasan, ana macem-macem cara sing nggawe gampang maca utawa nulis isi file. Tuladha:

Path path = Path.of("c:\\readme.txt");
List<String> list = Files.readAllLines(path);

for (String str : list)
   System.out.println(str);

6. Njupuk isi direktori

Cara sing paling menarik isih tetep. Iki digunakake kanggo njupuk file lan subdirektori ing direktori tartamtu.

Kita ngomong babagan newDirectoryStream()cara, sing ngasilake obyek khusus DirectoryStream<Path>. Wis iterator (!) sing bisa digunakake kanggo njupuk kabeh file lan subdirektori saka direktori tartamtu.

Iki luwih gampang tinimbang muni.

Path path = Path.of("c:\\windows");

try (DirectoryStream<Path> files = Files.newDirectoryStream(path)) {
   for (Path path : files)
      System.out.println(path);
}

Objek kasebut DirectoryStream<Path>nduweni rong sifat. Kaping pisanan, nduweni iterator sing ngasilake path file, lan kita bisa nggunakake obyek iki ing daur for-eachulang.

Lan kaloro, obyek iki minangka aliran data, mula kudu ditutup kanthi jelas nggunakake close()metode kasebut, utawa nyatakake panggunaan ing try-with-resourcesblok.

7. Files.newInputStreamcara

Diwiwiti karo Java 5, kelas FileInputStreamlan FileOutputStreamwis ora digunakake. Salah sawijining kekurangane yaiku nalika obyek saka kelas kasebut digawe, file langsung digawe ing disk. Lan kabeh pangecualian sing ana gandhengane karo nggawe file bisa uga dibuwang.

Mengko iki diakoni minangka dudu keputusan sing paling apik. Mulane, dianjurake kanggo nggunakake metode kelas sarana java.nio.Fileskanggo nggawe obyek file.

Mangkene perbandingan antarane pendekatan lawas lan pendekatan anyar kanggo nggawe file:

String src = "c:\\projects\\log.txt";
InputStream input = new FileInputStream(src);

String src = "c:\\projects\\log.txt";
InputStream input = Files.newInputStream( Path.of(src) );

Lan ana panggantos sing padha kanggo FileOutputStream:

String src = "c:\\projects\\log.txt";
OutputStream  output = new FileOutputStream( src );

String src = "c:\\projects\\log.txt";
OutputStream  output = Files.newOutputStream( Path.of( src ) );