File Handling in Java

⏱ Estimated reading time: 2 min

File handling in Java allows a program to read from and write to files, enabling data storage, retrieval, and manipulation outside the program. Java provides I/O streams and classes in java.io and java.nio packages for file operations.

1. Types of Files

• Text Files → Contain human-readable characters.

• Binary Files → Contain binary data like images, audio, or serialized objects.

2. Java File Handling Classes

Some commonly used classes for file handling:

3. Creating a File

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

public class Test {
    public static void main(String[] args) {
        try {
            File file = new File("example.txt");
            if (file.createNewFile()) {
                System.out.println("File created: " + file.getName());
            } else {
                System.out.println("File already exists.");
            }
        } catch (IOException e) {
            System.out.println("An error occurred.");
            e.printStackTrace();
        }
    }
}

4. Writing to a File

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

public class Test {
    public static void main(String[] args) {
        try {
            FileWriter writer = new FileWriter("example.txt");
            writer.write("Hello, Java File Handling!\n");
            writer.write("Second line of text.");
            writer.close();
            System.out.println("Successfully wrote to the file.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

5. Reading from a File

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

public class Test {
    public static void main(String[] args) {
        try {
            FileReader fr = new FileReader("example.txt");
            BufferedReader br = new BufferedReader(fr);
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line);
            }
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

6. File Operations

• Checking existence: file.exists()

• Getting file info: file.length(), file.getName(), file.getPath()

• Deleting a file: file.delete()

• Creating directories: file.mkdir() or file.mkdirs()

7. Advantages of File Handling

• Persistent storage of data.

• Data sharing between programs.

• Supports large data processing.

• Enables backup and recovery of information.

8. Conclusion

File handling in Java provides a robust mechanism to read, write, and manage files. By using classes from java.io and java.nio packages, developers can handle both text and binary files efficiently, making applications data-persistent and versatile.