File Handling

Java provides the java.io package for file handling.

The File Class

This class is an abstract representation of file and directory pathnames.

import java.io.File;

File myFile = new File("filename.txt");

Useful Methods

• canRead()
• canWrite()
• createNewFile()
• delete()
• exists()
• length()

Writing to a File

Use FileWriter.

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

try {
  FileWriter myWriter = new FileWriter("filename.txt");
  myWriter.write("Java is fun!");
  myWriter.close();
} catch (IOException e) {
  e.printStackTrace();
}

Reading from a File

Use Scanner (easiest) or FileReader.

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

File myObj = new File("filename.txt");
Scanner myReader = new Scanner(myObj);
while (myReader.hasNextLine()) {
  String data = myReader.nextLine();
  System.out.println(data);
}
myReader.close();

Interactive Code

Note: In a browser environment, file access is restricted. This code demonstrates the syntax.

Quiz

Next Steps

For advanced I/O (like sending Objects over a network), we need Streams & Serialization.