Java File Handling
Java File Handling
File handling in Java allows reading and writing data to files. Java provides the java.io and java.nio packages for file operations.
1. File Handling Classes in Java
Class Description
File Represents a file or directory path
FileReader Reads text files
FileWriter Writes text files
BufferedReader Reads text efficiently
BufferedWriter Writes text efficiently
Scanner Reads files using a scanner
PrintWriter Writes formatted text to a file
2. Creating a File
✅ Example: Creating a File using File Class
import java.io.File;
import java.io.IOException;
public class CreateFileExample {
public static void main(String[] args) {
try {
File myFile = new File("example.txt");
if (myFile.createNewFile()) {
System.out.println("File created: " + myFile.getName());
} else {
System.out.println("File already exists.");
}
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
💡 Output:
File created: example.txt
(If the file already exists, it will print: "File already exists.")
3. Writing to a File
✅ Example: Writing to a File using FileWriter
import java.io.FileWriter;
import java.io.IOException;
public class WriteFileExample {
public static void main(String[] args) {
try {
FileWriter writer = new FileWriter("example.txt");
writer.write("Hello, Java File Handling!\n");
writer.write("Writing to a file is easy.");
writer.close();
System.out.println("Successfully wrote to the file.");
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
💡 File Content (example.txt):
Hello, Java File Handling!
Writing to a file is easy.
4. Reading from a File
4.1 Using FileReader and BufferedReader
✅ Example: Reading a File using BufferedReader
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class ReadFileExample {
public static void main(String[] args) {
try {
BufferedReader reader = new BufferedReader(new FileReader("example.txt"));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
reader.close();
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
💡 Output (Reads example.txt content):
Hello, Java File Handling!
Writing to a file is easy.
4.2 Using Scanner Class
✅ Example: Reading a File using Scanner
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ScannerFileExample {
public static void main(String[] args) {
try {
File file = new File("example.txt");
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
System.out.println(scanner.nextLine());
}
scanner.close();
} catch (FileNotFoundException e) {
System.out.println("File not found.");
e.printStackTrace();
}
}
}
5. Appending to a File
✅ Example: Appending Text using FileWriter
import java.io.FileWriter;
import java.io.IOException;
public class AppendFileExample {
public static void main(String[] args) {
try {
FileWriter writer = new FileWriter("example.txt", true); // true enables appending
writer.write("\nAppending new data!");
writer.close();
System.out.println("Successfully appended to the file.");
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
💡 File Content (example.txt) after appending:
Hello, Java File Handling!
Writing to a file is easy.
Appending new data!
6. Deleting a File
✅ Example: Deleting a File using File Class
import java.io.File;
public class DeleteFileExample {
public static void main(String[] args) {
File file = new File("example.txt");
if (file.delete()) {
System.out.println("Deleted file: " + file.getName());
} else {
System.out.println("Failed to delete the file.");
}
}
}
7. Checking File Properties
✅ Example: Checking if a File Exists & Getting Properties
import java.io.File;
public class FilePropertiesExample {
public static void main(String[] args) {
File file = new File("example.txt");
if (file.exists()) {
System.out.println("File exists: " + file.getName());
System.out.println("Absolute Path: " + file.getAbsolutePath());
System.out.println("Writable: " + file.canWrite());
System.out.println("Readable: " + file.canRead());
System.out.println("File Size: " + file.length() + " bytes");
} else {
System.out.println("File does not exist.");
}
}
}
💡 Example Output:
File exists: example.txt
Absolute Path: C:\Users\YourUser\example.txt
Writable: true
Readable: true
File Size: 45 bytes
Summary
Operation Method
Create a File File.createNewFile()
Write to a File FileWriter.write()
Read a File BufferedReader.readLine(), Scanner.nextLine()
Append to a File FileWriter(file, true).write()
Delete a File File.delete()
Check File Properties file.exists(), file.canRead(), file.length()
Date: 2025-03-28 00:00:00.000000