1. import java.util.ArrayList;
  2. import java.util.List;
  3. import java.util.regex.Matcher;
  4. import java.util.regex.Pattern;
  6. public class URLValidator {
  8. /**
  9. * Validates a list of URLs with basic sanity checks.
  10. *
  11. * @param urls A list of URLs to validate.
  12. * @return A list of error messages, one for each invalid URL. Returns an empty list if all URLs are valid.
  13. */
  14. public static List<String> validateURLs(List<String> urls) {
  15. List<String> errors = new ArrayList<>();
  17. if (urls == null) {
  18. errors.add("Input URL list is null.");
  19. return errors;
  20. }
  22. for (String url : urls) {
  23. if (url == null || url.isEmpty()) {
  24. errors.add("URL is null or empty: " + url);
  25. continue;
  26. }
  28. if (!isValidURLFormat(url)) {
  29. errors.add("Invalid URL format: " + url);
  30. } else {
  31. //Further checks can be added here (e.g., domain existence, protocol check)
  32. }
  33. }
  35. return errors;
  36. }
  38. private static boolean isValidURLFormat(String url) {
  39. // Basic regex for URL format validation. Not exhaustive.
  40. String regex = "^(http(s)?://)?([\\w-]+\\.)+[\\w-]+(/[\\w- ./?%&=]*)?$";
  41. Pattern pattern = Pattern.compile(regex);
  42. Matcher matcher = pattern.matcher(url);
  43. return matcher.matches();
  44. }
  47. public static void main(String[] args) {
  48. List<String> urls = new ArrayList<>();
  49. urls.add("https://www.example.com");
  50. urls.add("http://example.com");
  51. urls.add("invalid-url");
  52. urls.add(" ");
  53. urls.add(null);
  54. urls.add("https://example.com/path with spaces");
  57. List<String> errors = validateURLs(urls);
  59. if (errors.isEmpty()) {
  60. System.out.println("All URLs are valid.");
  61. } else {
  62. System.out.println("Invalid URLs:");
  63. for (String error : errors) {
  64. System.out.println(error);
  65. }
  66. }
  67. }
  68. }

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