The I/o classes and Interfaces

The I/O Classes and Interfaces

Ismoilov Do’stmurod

https://t.me/Ismoilov9922

I/O -

I/O - interfaces are defined by java.io

I/O - constructors of File class

• File(String directoryPath)
• File(String directoryPath, String filename)
• File(File dirObj, String filename)
• File(URI uriObj)

I/O - Example of File objects

• File f1 = new File("/");
• File f2 = new File("/","autoexec.bat");
• File f3 = new File(f1,"autoexec.bat");

I/O - Note

Fayl manzilida ajratuvchi belgisi Windows va Unixda bir-birdan farq qiladi. Windowsda bu belgi “\” kabi bo’lsa, Unixda esa aksi “/” kabidir. Javaning windowsdagi versiyasidan foydalanayotganda “\” belgi \\ belgi bilan yozilishi kerakligini unutmaslik kerak.

I/O - File methods

• getName() – Fayl nomi qaytaradi
• getPath() – Fayl manzilini qaytaradi
• getAbsolutePath() – Absolut nomi
• getParent() – Bosh manzili
• exists() – mavjudlikka tekshirish
• canWrite() – yozish mumkinlikka tekshirish
• canRead() – o’qish mumkinlikka tekshirish
• isDirectory() – Direktoriyalikka tekshirish
• isFile() – fayllikka tekshirish
• isAbsolute() – Absolutlikka tekshirish
• lastModified() – o’zgartirilgan vaqti (Unix time)
• length() – fayl uzunligi baytlarda

I/O - File methods

p("File Name: " + f1.getName());
p("Path: " + f1.getPath());
p("Absolute Path: " + f1.getAbsolutePath());
p("Parent: " + f1.getParent());
p(f1.exists() ? "exists" : "does not exist");

I/O -

• boolean renameTo(File newName)
• boolean delete( ) – o’chirish
• void deleteOnExit( ) – Object bilan bog’langan fayl o’chadi va Virtual mashina yopiladi.
• long getFreeSpace( ) – Bo’shjoyni olish
• long getTotalSpace( ) – Umumiy joyni olish
• long getUsableSpace( ) – foydalanish mumkin bo’lgan bo’sh joylar
• boolean isHidden( ) – ko’rmaslikka tekshirish
• boolean setLastModified(long millisec) – O’zgartiligan vaqtni o’zgartirish (1970 yil sanoq boshi)
• boolean setReadOnly( ) – faqat o’qish ruxsatini o’rnatish

I/O - Directories

• toPath( ) – Bu method JDK 7 dan boshlab qo’shilgan va Path sinfi objectini qaytaradi.
• String[ ] list( ) – Tarkibida mavjud bo’lgan fayl va direktoriyalarni ro’yhatini qaytaradi.

I/O - Directories

File file = new File("D:\\"); String s[] = file.list(); for (String value : s) { System.out.println(value); File file1 = new File("D:\\" + value); if (file1.isDirectory()){ System.out.println("Directory: " + file1.getName()); } if (file1.isFile()){ System.out.println("File: " + file1.getName()); } }

I/O - All files

public static ArrayList getAllFileInDirectory(String rootPath) { ArrayList list = new ArrayList<>(); File file = new File(rootPath); String s[] = file.list(); if (s != null) { for (String value : s) { File file1 = new File(rootPath + "\\" + value); if (file1.isDirectory()) { list.addAll(getAllFileInDirectory(rootPath + "\\" + value)); } if (file1.isFile()) { list.add(file.getPath() + "\\" + value); } } } return list; }

I/O - All files

ArrayList list = getAllFileInDirectory("D:\\"); list.forEach(System.out::println);
Berilgan katalogdagi barcha fayllarni ko’rish. Masalan D:\ diskdagi barcha fayllarni ko’rish uchun:

I/O - FilenameFilter

boolean accept(File directory, String filename)
public class OnlyExt implements FilenameFilter { String ext; public OnlyExt(String ext) { this.ext = "." + ext; } public boolean accept(File dir, String name) { return name.endsWith(ext); } }

I/O - FilenameFilter

String dirname = "D:\\"; File f1 = new File(dirname); FilenameFilter only = new OnlyExt("cpp"); String s[] = f1.list(only); for (String value : s) { System.out.println(value); }

I/O - Stream

• Ma’lumotlarni oqimli ketma-ketlikda tas’virlash mumkin. Ikki xil oqim mavjud:
• InPutStream − bundan foydalaniladi ma’lumotlarni manbaadan o’qish uchun.
• OutPutStream − bunday foydalaniladi ma’lumotlarni yozish uchun.

I/O - Byte Streams

FileInputStream in = null; FileOutputStream out = null; try { in = new FileInputStream("input.txt"); out = new FileOutputStream("output.txt"); int c; while ((c = in.read()) != -1) { out.write(c); } }finally { if (in != null) { in.close(); } if (out != null) { out.close(); } }

I/O - Character Streams

FileReader in = null; FileWriter out = null; try { in = new FileReader("input.txt"); out = new FileWriter("output.txt"); int c; while ((c = in.read()) != -1) { out.write(c); } }finally { if (in != null) { in.close(); } if (out != null) { out.close(); } }