FileCompressionDecompressionTool.java

import java.io.*;
import java.util.Scanner;

class RLECompressor {

    public static String compress(String data) {

        if (data == null || data.isEmpty()) {
            return "";
        }

        StringBuilder result = new StringBuilder();
        int count = 1;

        for (int i = 0; i < data.length() - 1; i++) {
            if (data.charAt(i) == data.charAt(i + 1)) {
                count++;
            } else {
                result.append(data.charAt(i)).append(count);
                count = 1;
            }
        }

        result.append(data.charAt(data.length() - 1)).append(count);
        return result.toString();
    }
}

class RLEDecompressor {

    public static String decompress(String data) {

        StringBuilder result = new StringBuilder();

        for (int i = 0; i < data.length();) {
            char ch = data.charAt(i);
            StringBuilder num = new StringBuilder();

            i++;
            while (i < data.length() && Character.isDigit(data.charAt(i))) {
                num.append(data.charAt(i));
                i++;
            }

            int count = Integer.parseInt(num.toString());

            for (int j = 0; j < count; j++) {
                result.append(ch);
            }
        }

        return result.toString();
    }
}

class FileCompressionDecompressionTool {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int choice;

        do {
            System.out.println("\n1. Compress File");
            System.out.println("2. Decompress File");
            System.out.println("3. Exit");
            System.out.print("Enter choice: ");
            choice = sc.nextInt();
            sc.nextLine();

            switch (choice) {

                case 1:
                    try {
                        System.out.print("Enter input file name: ");
                        String inFile = sc.nextLine();

                        System.out.print("Enter output file name: ");
                        String outFile = sc.nextLine();

                        BufferedReader reader = new BufferedReader(new FileReader(inFile));
                        BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));

                        String line;
                        while ((line = reader.readLine()) != null) {
                            writer.write(RLECompressor.compress(line));
                            writer.newLine();
                        }

                        reader.close();
                        writer.close();

                        System.out.println("Compression completed");
                    } catch (IOException e) {
                        System.out.println("Error: " + e.getMessage());
                    }
                    break;

                case 2:
                    try {
                        System.out.print("Enter compressed file name: ");
                        String inFile = sc.nextLine();

                        System.out.print("Enter output file name: ");
                        String outFile = sc.nextLine();

                        BufferedReader reader = new BufferedReader(new FileReader(inFile));
                        BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));

                        String line;
                        while ((line = reader.readLine()) != null) {
                            writer.write(RLEDecompressor.decompress(line));
                            writer.newLine();
                        }

                        reader.close();
                        writer.close();

                        System.out.println("Decompression completed");
                    } catch (IOException e) {
                        System.out.println("Error: " + e.getMessage());
                    }
                    break;

                case 3:
                    System.out.println("Program terminated");
                    break;

                default:
                    System.out.println("Invalid choice");
            }

        } while (choice != 3);

        sc.close();
    }
}