Java Course Navigation Java File Handling | CrackEase

File Handling in Java

File handling in Java involves performing operations on files stored on the filesystem — for example creating, reading, writing, updating and deleting files.

Java provides a rich set of I/O classes and utilities (in packages like java.io and java.nio.file) that make working with files straightforward and robust.

File Input and Output Streams

Java handles raw byte streams and character streams. For byte-level operations use FileInputStream and FileOutputStream. For character-based I/O use readers and writers such as FileReader, FileWriter, BufferedReader and BufferedWriter.

Buffered classes improve performance by reducing the number of physical reads/writes. For modern code consider using java.nio.file.Files utilities (since Java 7) for many common file tasks.

File Handling in Java

Common file operations include:

Creating and deleting files or directories
Reading from files (byte or character streams)
Writing to files (overwriting or appending)
Checking file existence, size, permissions and metadata

Frequently used classes: File, FileInputStream, FileOutputStream, FileReader, FileWriter, BufferedReader, BufferedWriter, and the Files utility class under java.nio.file.

File Handling in Java (Summary)

Best practices when working with files:

Always close streams (use try-with-resources since Java 7).
Prefer buffered streams/writers for better performance.
Validate paths and handle exceptions gracefully.
Use java.nio.file APIs for modern, robust file operations.

Reading File

Example — reading a file character by character using FileReader:


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

public class ReadFromFile {
    public static void main(String[] args) {
        File file = new File("example.txt");
        try (FileReader reader = new FileReader(file)) {
            int character;
            while ((character = reader.read()) != -1) {
                System.out.print((char) character);
            }
        } catch (IOException e) {
            System.out.println("An error occurred while reading the file.");
            e.printStackTrace();
        }
    }
}

Writing File

Example — writing text to a file using BufferedWriter:


import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class WriteToFile {
    public static void main(String[] args) {
        File file = new File("example.txt");
        try (BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(file))) {
            bufferedWriter.write("Hello, world!");
            System.out.println("Data written to file successfully.");
        } catch (IOException e) {
            System.out.println("An error occurred while writing to the file.");
            e.printStackTrace();
        }
    }
}

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