1. import java.io.*;
  2. import java.util.ArrayList;
  3. import java.util.HashMap;
  4. import java.util.List;
  5. import java.util.Map;
  7. public class TaskQueueRestorer {
  9. private static final String DEFAULT_FILE_EXTENSION = ".taskqueue";
  11. /**
  12. * Restores task queue data from a file.
  13. *
  14. * @param queueName The name of the task queue.
  15. * @param filePath The path to the file containing the queue data.
  16. * @return A list of tasks in the queue, or null if an error occurred.
  17. */
  18. public static List<String> restoreQueue(String queueName, String filePath) {
  19. List<String> tasks = new ArrayList<>();
  21. try (FileInputStream fis = new FileInputStream(filePath);
  22. ObjectInputStream ois = new ObjectInputStream(fis)) {
  24. // Read the queue data from the file.
  25. Object queueObject = ois.readObject();
  27. if (queueObject instanceof List) {
  28. tasks = (List<String>) queueObject; // Cast to List<String>
  29. } else {
  30. System.err.println("Error: Invalid queue data format in file: " + filePath);
  31. return null; // Indicate an error
  32. }
  34. } catch (IOException | ClassNotFoundException e) {
  35. System.err.println("Error restoring queue from file: " + filePath + ". " + e.getMessage());
  36. return null; // Indicate an error
  37. }
  39. return tasks;
  40. }
  42. /**
  43. * Saves task queue data to a file for backup.
  44. *
  45. * @param queueName The name of the task queue.
  46. * @param tasks The list of tasks to save.
  47. * @param filePath The path to the file to save the queue data to.
  48. */
  49. public static void saveQueue(String queueName, List<String> tasks, String filePath) {
  50. try (FileOutputStream fos = new FileOutputStream(filePath);
  51. ObjectOutputStream oos = new ObjectOutputStream(fos)) {
  53. oos.writeObject(tasks);
  54. System.out.println("Queue '" + queueName + "' saved to: " + filePath);
  56. } catch (IOException e) {
  57. System.err.println("Error saving queue to file: " + filePath + ". " + e.getMessage());
  58. }
  59. }
  61. public static void main(String[] args) {
  62. // Example usage
  63. String queueName = "myQueue";
  64. String filePath = "myQueue" + DEFAULT_FILE_EXTENSION;
  66. // Restore the queue
  67. List<String> restoredTasks = restoreQueue(queueName, filePath);
  69. if (restoredTasks != null) {
  70. System.out.println("Restored tasks:");
  71. for (String task : restoredTasks) {
  72. System.out.println(task);
  73. }
  74. } else {
  75. System.out.println("Queue restoration failed.");
  76. }
  78. // Save the queue (for demonstration)
  79. List<String> tasksToSave = new ArrayList<>();
  80. tasksToSave.add("Task 1");
  81. tasksToSave.add("Task 2");
  82. tasksToSave.add("Task 3");
  83. saveQueue(queueName, tasksToSave, filePath);
  85. }
  86. }

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