org.apache.commons.io.filefilter

## Class RegexFileFilter

- java.lang.Object
- - org.apache.commons.io.filefilter.AbstractFileFilter
  - - org.apache.commons.io.filefilter.RegexFileFilter

- All Implemented Interfaces:
    FileFilter, FilenameFilter, Serializable, FileVisitor<Path>, PathFilter, PathVisitor, IOFileFilter

      public class RegexFileFilter
      extends AbstractFileFilter
      implements Serializable

  Filters files using supplied regular expression(s).

  See java.util.regex.Pattern for regex matching rules.

  ## Using Classic IO

  e.g.

       File dir = new File(".");
       FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
       File[] files = dir.listFiles(fileFilter);
       for (String file : files) {
           System.out.println(file);
       }

  ## Using NIO

       final Path dir = Paths.get("");
       final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$"));
       //
       // Walk one dir
       Files.walkFileTree(dir, Collections.emptySet(), 1, visitor);
       System.out.println(visitor.getPathCounters());
       System.out.println(visitor.getFileList());
       //
       visitor.getPathCounters().reset();
       //
       // Walk dir tree
       Files.walkFileTree(dir, visitor);
       System.out.println(visitor.getPathCounters());
       System.out.println(visitor.getDirList());
       System.out.println(visitor.getFileList());

  Since:
    1.4
  See Also:
    Serialized Form

- - ### Field Summary

    - ### Fields inherited from interface org.apache.commons.io.filefilter.IOFileFilter

      `EMPTY_STRING_ARRAY`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `RegexFileFilter(Pattern pattern)` Construct a new regular expression filter for a compiled regular expression
    `RegexFileFilter(String pattern)` Construct a new regular expression filter.
    `RegexFileFilter(String pattern, int flags)` Construct a new regular expression filter with the specified flags.
    `RegexFileFilter(String pattern, IOCase caseSensitivity)` Construct a new regular expression filter with the specified flags case sensitivity.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `accept(File dir, String name)` Checks to see if the file name matches one of the regular expressions.
    `FileVisitResult` | `accept(Path path, BasicFileAttributes attributes)` Checks to see if the file name matches one of the regular expressions.

    - ### Methods inherited from class org.apache.commons.io.filefilter.AbstractFileFilter

      `accept, handle, postVisitDirectory, preVisitDirectory, toString, visitFile, visitFileFailed`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface org.apache.commons.io.filefilter.IOFileFilter

      `and, negate, or`

- - ### Constructor Detail

    - #### RegexFileFilter

          public RegexFileFilter(Pattern pattern)

      Construct a new regular expression filter for a compiled regular expression
      Parameters:
        `pattern` - regular expression to match
      Throws:
        `IllegalArgumentException` - if the pattern is null

    - #### RegexFileFilter

          public RegexFileFilter(String pattern)

      Construct a new regular expression filter.
      Parameters:
        `pattern` - regular string expression to match
      Throws:
        `IllegalArgumentException` - if the pattern is null

    - #### RegexFileFilter

          public RegexFileFilter(String pattern,
                                 int flags)

      Construct a new regular expression filter with the specified flags.
      Parameters:
        `pattern` - regular string expression to match
        `flags` - pattern flags - e.g. `Pattern.CASE_INSENSITIVE`
      Throws:
        `IllegalArgumentException` - if the pattern is null

    - #### RegexFileFilter

          public RegexFileFilter(String pattern,
                                 IOCase caseSensitivity)

      Construct a new regular expression filter with the specified flags case sensitivity.
      Parameters:
        `pattern` - regular string expression to match
        `caseSensitivity` - how to handle case sensitivity, null means case-sensitive
      Throws:
        `IllegalArgumentException` - if the pattern is null

  - ### Method Detail

    - #### accept

          public boolean accept(File dir,
                                String name)

      Checks to see if the file name matches one of the regular expressions.
      Specified by:
        `accept` in interface `FilenameFilter`
      Specified by:
        `accept` in interface `IOFileFilter`
      Overrides:
        `accept` in class `AbstractFileFilter`
      Parameters:
        `dir` - the file directory (ignored)
        `name` - the file name
      Returns:
        true if the file name matches one of the regular expressions

    - #### accept

          public FileVisitResult accept(Path path,
                                        BasicFileAttributes attributes)

      Checks to see if the file name matches one of the regular expressions.
      Specified by:
        `accept` in interface `PathFilter`
      Specified by:
        `accept` in interface `IOFileFilter`
      Parameters:
        `path` - the path
        `attributes` - the path attributes
      Returns:
        true if the file name matches one of the regular expressions

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