Java fayllarni o‘qish

Faylni o‘qish

Oldingi boblarda faylni qanday yaratish va unga yozishni o‘rgandingiz.

Quyidagi misolda oldingi bobda yaratgan matnli faylimizning tarkibini o‘qish uchun Scanner sinfidan foydalanamiz:

import java.io.File;                  // Import the File class
import java.io.FileNotFoundException; // Import this class to handle errors
import java.util.Scanner;             // Import the Scanner class to read text files

public class ReadFile {
  public static void main(String[] args) {
    File myObj = new File("filename.txt");

    // try-with-resources: Scanner will be closed automatically
    try (Scanner myReader = new Scanner(myObj)) {
      while (myReader.hasNextLine()) {
        String data = myReader.nextLine();
        System.out.println(data);
      }
    } catch (FileNotFoundException e) {
      System.out.println("An error occurred.");
      e.printStackTrace();
    }
  }
}

Tushuntirish: Bu dastur filename.txt nomli faylni ochadi va uni Scanner yordamida qatorma-qator o‘qiydi. Har bir qator konsolga chiqariladi. Agar fayl topilmasa, dastur buning o‘rniga "An error occurred." deb chiqaradi.

Fayl haqida ma’lumot olish

Fayl haqida ko‘proq ma’lumot olish uchun File metodlarining istalganidan foydalaning:

import java.io.File;  // Import the File class

public class GetFileInfo { 
  public static void main(String[] args) {
    File myObj = new File("filename.txt");
    if (myObj.exists()) {
      System.out.println("File name: " + myObj.getName());
      System.out.println("Absolute path: " + myObj.getAbsolutePath());
      System.out.println("Writeable: " + myObj.canWrite());
      System.out.println("Readable " + myObj.canRead());
      System.out.println("File size in bytes " + myObj.length());
    } else {
      System.out.println("The file does not exist.");
    }
  }
}

Fayllarni o‘qishning boshqa usullari

Java tilida fayllarni o‘qish uchun foydalanishingiz mumkin bo‘lgan bir nechta sinf bor:

• Scanner — oddiy matn uchun hamda sonlar yoki so‘zlarni oson ajratib olmoqchi bo‘lganingizda eng yaxshisi.
• BufferedReader — katta matnli fayllar uchun eng yaxshisi, chunki u tezroq ishlaydi va qatorma-qator o‘qiydi.
• FileInputStream — ikkilik ma’lumotlar (rasmlar, audio, PDF fayllar) uchun yoki xom baytlarni to‘liq nazorat qilish kerak bo‘lganda eng yaxshisi.

FileInputStream va BufferedReader haqida keyingi boblarda batafsil bilib olasiz.