Module 37: File Handling in Java

📂 Introduction

Java provides powerful classes for reading and writing files in the java.io and java.nio packages. File handling is essential for data persistence and working with external data sources.

📄 Reading from a File

                    import java.io.File;
                    import java.io.FileNotFoundException;
                    import java.util.Scanner;
                    
                    public class ReadFileExample {
                      public static void main(String[] args) {
                        try {
                          File file = new File("example.txt");
                          Scanner reader = new Scanner(file);
                          while (reader.hasNextLine()) {
                            String data = reader.nextLine();
                            System.out.println(data);
                          }
                          reader.close();
                        } catch (FileNotFoundException e) {
                          System.out.println("An error occurred.");
                          e.printStackTrace();
                        }
                      }
                    }

📝 Writing to a File

                    import java.io.FileWriter;
                    import java.io.IOException;
                    
                    public class WriteFileExample {
                      public static void main(String[] args) {
                        try {
                          FileWriter writer = new FileWriter("output.txt");
                          writer.write("This is written to the file.");
                          writer.close();
                          System.out.println("Successfully wrote to the file.");
                        } catch (IOException e) {
                          System.out.println("An error occurred.");
                          e.printStackTrace();
                        }
                      }
                    }

📌 Tips

• Always close file readers/writers to avoid memory leaks.
• Use try-with-resources for automatic resource management.
• Check if the file exists before reading it.