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28FileHandling

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Chalanges
Chalanges
 
 
FileRead
FileRead
 
 
FileWrite
FileWrite
 
 
example.txt
example.txt
 
 
readme.md
readme.md
 
 
sujit.txt
sujit.txt
 
 

readme.md

☕ Java Lesson – File Handling (Read & Write)

Is lesson me hum cover karenge:

  • File handling kya hota hai
  • File class ka use
  • File create karna
  • File me write karna
  • File se read karna
  • BufferedReader vs FileReader
  • Best practices

1️⃣ File Handling Kya Hota Hai?

File handling ka matlab hai:

program ke through file create, read, write aur delete karna

Java me file handling ke liye:

java.io package use hota hai

2️⃣ Required Imports

import java.io.File;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.IOException;

3️⃣ File Create Karna

import java.io.File;
import java.io.IOException;

public class Test {

    public static void main(String[] args) {

        try {
            File file = new File("data.txt");

            if(file.createNewFile()){
                System.out.println("File created");
            } else {
                System.out.println("File already exists");
            }

        } catch(IOException e){
            System.out.println("Error creating file");
        }
    }
}

4️⃣ File Me Write Karna

File write karne ke liye:

FileWriter use hota hai

Example:

import java.io.FileWriter;
import java.io.IOException;

public class Test {

    public static void main(String[] args) {

        try {
            FileWriter writer = new FileWriter("data.txt");

            writer.write("Hello Sujit");
            writer.close();

            System.out.println("Data written");
        } catch(IOException e){
            System.out.println("Write error");
        }
    }
}

5️⃣ File Read Karna – FileReader

import java.io.FileReader;
import java.io.IOException;

public class Test {

    public static void main(String[] args) {

        try {
            FileReader reader = new FileReader("data.txt");

            int ch;
            while((ch = reader.read()) != -1){
                System.out.print((char) ch);
            }

            reader.close();
        } catch(IOException e){
            System.out.println("Read error");
        }
    }
}

6️⃣ File Read Karna – BufferedReader (Better Way)

BufferedReader fast aur efficient hota hai.

import java.io.*;

public class Test {

    public static void main(String[] args) {

        try {
            BufferedReader br = new BufferedReader(new FileReader("data.txt"));

            String line;

            while((line = br.readLine()) != null){
                System.out.println(line);
            }

            br.close();
        } catch(IOException e){
            System.out.println("Error reading file");
        }
    }
}

7️⃣ Append Mode Me Write Karna

FileWriter writer = new FileWriter("data.txt", true);

Ye existing data delete nahi karta.

8️⃣ File Information Lena

File file = new File("data.txt");

System.out.println(file.getName());
System.out.println(file.getAbsolutePath());
System.out.println(file.length());

9️⃣ File Delete Karna

File file = new File("data.txt");

if(file.delete()){
    System.out.println("File deleted");
}

🔟 Try-with-resources (Best Practice)

Ye automatically file close kar deta hai.

try(FileWriter writer = new FileWriter("data.txt")) {
    writer.write("Hello");
}
catch(IOException e){
    System.out.println("Error");
}

1️⃣1️⃣ Complete Program – Write then Read

import java.io.*;

class Test {

    public static void main(String[] args) {

        try {

            FileWriter fw = new FileWriter("data.txt");
            fw.write("Java File Handling");
            fw.close();

            BufferedReader br = new BufferedReader(new FileReader("data.txt"));
            String line;

            while((line = br.readLine()) != null){
                System.out.println(line);
            }

            br.close();

        } catch(IOException e){
            System.out.println("Error");
        }
    }
}

1️⃣2️⃣ File Handling Classes Summary

Class Purpose
File file create, info, delete
FileWriter write data
FileReader read characters
BufferedReader fast reading

1️⃣3️⃣ Checked Exception in File Handling

File operations me:

IOException aata hai

Isliye:

try-catch ya throws mandatory hai

🎯 Interview Questions

  1. FileWriter aur FileReader me difference kya hai?
  2. BufferedReader fast kyun hota hai?
  3. Append mode kya hota hai?
  4. Try-with-resources kya hai?

🧾 Lesson Summary

Is lesson me humne seekha:

✔ File create karna
✔ File me data write karna
✔ File se data read karna
✔ BufferedReader ka use
✔ Try-with-resources best practice

File handling Java me persistent storage aur logging ke liye essential hai.