Java File Handling Explained in Depth: Read and Write Files with Examples

Java File Handling Explained in Depth

Author: Gursehbaj Singh | Blog: DevMode

File Handling in Java allows us to create, read, write, and delete files. It is very important for real-world applications such as saving data, logging, and reading configuration files.

Why File Handling is Important?

• Store data permanently
• Read user information from files
• Create logs and reports
• Work with databases and backups

Java File Class

The File class is used to represent a file or directory.

import java.io.File;

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

Creating a File

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

class CreateFile {
    public static void main(String[] args) {
        try {
            File file = new File("myfile.txt");
            if (file.createNewFile()) {
                System.out.println("File created successfully");
            } else {
                System.out.println("File already exists");
            }
        } catch (IOException e) {
            System.out.println("Error while creating file");
        }
    }
}

Writing to a File

We use FileWriter to write data into a file.

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

class WriteFile {
    public static void main(String[] args) {
        try {
            FileWriter writer = new FileWriter("myfile.txt");
            writer.write("Welcome to DevMode Java File Handling");
            writer.close();
            System.out.println("Data written successfully");
        } catch (IOException e) {
            System.out.println("Error while writing to file");
        }
    }
}

Reading from a File

We use FileReader and Scanner to read data.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

class ReadFile {
    public static void main(String[] args) {
        try {
            File file = new File("myfile.txt");
            Scanner sc = new Scanner(file);
            while (sc.hasNextLine()) {
                String data = sc.nextLine();
                System.out.println(data);
            }
            sc.close();
        } catch (FileNotFoundException e) {
            System.out.println("File not found");
        }
    }
}

Appending Data to File

FileWriter writer = new FileWriter("myfile.txt", true);
writer.write("\nLearning Java is fun!");
writer.close();

Deleting a File

File file = new File("myfile.txt");
if (file.delete()) {
    System.out.println("File deleted");
} else {
    System.out.println("Failed to delete file");
}

BufferedWriter for Fast Writing

import java.io.BufferedWriter;
import java.io.FileWriter;

BufferedWriter bw = new BufferedWriter(new FileWriter("data.txt"));
bw.write("Buffered writing in Java");
bw.close();

BufferedReader for Fast Reading

import java.io.BufferedReader;
import java.io.FileReader;

BufferedReader br = new BufferedReader(new FileReader("data.txt"));
String line;
while((line = br.readLine()) != null) {
    System.out.println(line);
}
br.close();

Exception Handling in File Handling

Always handle IOExceptions to avoid program crash.

Best Practices

• Always close files after use
• Use try-with-resources
• Handle exceptions properly
• Do not hardcode file paths

Conclusion

File handling is a core skill in Java. By learning how to create, read, write, append, and delete files, you can build real applications like text editors, log systems, and data storage programs.