Use final.

Author: Gary Gregory

src/main/java/org/apache/commons/io/FileUtils.java

@@ -2820,7 +2820,7 @@ public static File[] toFiles(final URL... urls) {
         return files;
     }
 
-    private static List<File> toList(Stream<File> stream) {
+    private static List<File> toList(final Stream<File> stream) {
         return stream.collect(Collectors.toList());
     }
 

src/main/java/org/apache/commons/io/file/CountingPathVisitor.java

@@ -75,7 +75,7 @@ public CountingPathVisitor(final PathCounters pathCounter) {
      * @param dirFilter Filters which directories to count.
      * @since 2.9.0
      */
-    public CountingPathVisitor(final PathCounters pathCounter, final PathFilter fileFilter, PathFilter dirFilter) {
+    public CountingPathVisitor(final PathCounters pathCounter, final PathFilter fileFilter, final PathFilter dirFilter) {
         super();
         this.pathCounters = Objects.requireNonNull(pathCounter, "pathCounter");
         this.fileFilter = Objects.requireNonNull(fileFilter, "fileFilter");
@@ -115,7 +115,7 @@ public FileVisitResult postVisitDirectory(final Path dir, final IOException exc)
     }
 
     @Override
-    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attributes) throws IOException {
+    public FileVisitResult preVisitDirectory(final Path dir, final BasicFileAttributes attributes) throws IOException {
         final FileVisitResult accept = dirFilter.accept(dir, attributes);
         return accept != FileVisitResult.CONTINUE ? FileVisitResult.SKIP_SUBTREE : FileVisitResult.CONTINUE;
     }

src/main/java/org/apache/commons/io/file/PathUtils.java

@@ -899,7 +899,7 @@ public static <T extends FileVisitor<? super Path>> T visitFileTree(final T visi
      * @since 2.9.0
      */
     public static Stream<Path> walk(final Path start, final PathFilter pathFilter, final int maxDepth,
-        boolean readAttributes, final FileVisitOption... options) throws IOException {
+        final boolean readAttributes, final FileVisitOption... options) throws IOException {
         return Files.walk(start, maxDepth, options).filter(path -> pathFilter.accept(path,
             readAttributes ? readBasicFileAttributesQuietly(path) : null) == FileVisitResult.CONTINUE);
     }

src/main/java/org/apache/commons/io/filefilter/PathEqualsFileFilter.java

@@ -45,12 +45,12 @@ public PathEqualsFileFilter(final Path file) {
     }
 
     @Override
-    public boolean accept(File file) {
+    public boolean accept(final File file) {
         return Objects.equals(this.path, file.toPath());
     }
 
     @Override
-    public FileVisitResult accept(Path path, BasicFileAttributes attributes) {
+    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
         return toFileVisitResult(Objects.equals(this.path, path), path);
     }
 }

src/test/java/org/apache/commons/io/FileUtilsTestCase.java

@@ -169,7 +169,7 @@ private void backDateFile10Minutes(final File testFile) throws IOException {
         assertNotEquals(getLastModifiedMillis(testFile), lastModified1, "Should have changed source date");
     }
 
-    private void consumeRemaining(Iterator<File> iterator) {
+    private void consumeRemaining(final Iterator<File> iterator) {
         if (iterator != null) {
             iterator.forEachRemaining(e -> {});
         }
@@ -221,12 +221,12 @@ private String getName() {
     }
 
     private void iterateFilesAndDirs(final File dir, final IOFileFilter fileFilter,
-        final IOFileFilter dirFilter, Collection<File> expectedFilesAndDirs) {
+        final IOFileFilter dirFilter, final Collection<File> expectedFilesAndDirs) {
         Iterator<File> iterator;
         int filesCount = 0;
         iterator = FileUtils.iterateFilesAndDirs(dir, fileFilter, dirFilter);
         try {
-            List<File> actualFiles = new ArrayList<>();
+            final List<File> actualFiles = new ArrayList<>();
             while (iterator.hasNext()) {
                 filesCount++;
                 final File file = iterator.next();
@@ -1919,7 +1919,7 @@ public void testIterateFilesAndDirs() throws IOException {
             iterateFilesAndDirs(subDir1, fileFilterAllFiles, fileFilterAllDirs, expectedFilesAndDirs);
             //
             // "*.txt" and "*"
-            int filesCount;
+            final int filesCount;
             expectedFilesAndDirs = Arrays.asList(subDir1, subDir2, someFile, subDir3, subDir4);
             iterateFilesAndDirs(subDir1, fileFilterExtTxt, fileFilterAllDirs, expectedFilesAndDirs);
             //