logback-android/src/main/java/ch/qos/logback/core/rolling/helper/FileFilterUtil.java
public static File[] filesInFolderMatchingStemRegex(File file,
      final String stemRegex) {

    if (file == null) {
      return new File[0];
    }
    if (!file.exists() || !file.isDirectory()) {
      return new File[0];
    }
    return file.listFiles(new FilenameFilter() {
      public boolean accept(File dir, String name) {
        return name.matches(stemRegex);
      }
    });
  }
public static File[] filesInFolderMatchingStemRegex(File file,
      final String stemRegex) {

    if (file == null) {
      return new File[0];
    }
    if (!file.exists() || !file.isDirectory()) {
      return new File[0];
    }
    return file.listFiles(new FilenameFilter() {
      public boolean accept(File dir, String name) {
        return name.matches(stemRegex);
      }
    });
  }
Return the set of files matching the stemRegex as found in 'directory'. A
stemRegex does not contain any slash characters or any folder separators.

@param file folder's file object
@param stemRegex regex file pattern to match
@return matching files