Use final.

src/main/java/org/apache/commons/collections4/CollectionUtils.java

@@ -951,7 +951,7 @@ public static <O, R extends Collection<? super O>> R select(final Iterable<? ext
      * @since 4.1
      */
     public static <O, R extends Collection<? super O>> R select(final Iterable<? extends O> inputCollection,
-            final Predicate<? super O> predicate, R outputCollection, R rejectedCollection) {
+            final Predicate<? super O> predicate, final R outputCollection, final R rejectedCollection) {
 
         if (inputCollection != null && predicate != null) {
             for (final O element : inputCollection) {
@@ -1273,7 +1273,7 @@ public static <T> T get(final Iterable<T> iterable, final int index) {
      * @throws IllegalArgumentException if the object type is invalid
      */
     public static Object get(final Object object, final int index) {
-        int i = index;
+        final int i = index;
         if (i < 0) {
             throw new IndexOutOfBoundsException("Index cannot be negative: " + i);
         }
@@ -1534,8 +1534,8 @@ public static int maxSize(final Collection<? extends Object> coll) {
      * @throws NullPointerException if either collection is null
      * @since 4.0
      */
-    public static <O extends Comparable<? super O>> List<O> collate(Iterable<? extends O> a,
-                                                                    Iterable<? extends O> b) {
+    public static <O extends Comparable<? super O>> List<O> collate(final Iterable<? extends O> a,
+                                                                    final Iterable<? extends O> b) {
         return collate(a, b, ComparatorUtils.<O>naturalComparator(), true);
     }
 
@@ -1715,7 +1715,7 @@ public static <E> Collection<E> retainAll(final Iterable<E> collection,
 
         final Transformer<E, EquatorWrapper<E>> transformer = new Transformer<E, EquatorWrapper<E>>() {
             @Override
-            public EquatorWrapper<E> transform(E input) {
+            public EquatorWrapper<E> transform(final E input) {
                 return new EquatorWrapper<>(equator, input);
             }
         };
@@ -1791,7 +1791,7 @@ public static <E> Collection<E> removeAll(final Iterable<E> collection,
 
         final Transformer<E, EquatorWrapper<E>> transformer = new Transformer<E, EquatorWrapper<E>>() {
             @Override
-            public EquatorWrapper<E> transform(E input) {
+            public EquatorWrapper<E> transform(final E input) {
                 return new EquatorWrapper<>(equator, input);
             }
         };

src/main/java/org/apache/commons/collections4/IterableUtils.java

@@ -172,7 +172,7 @@ public static <E> Iterable<E> chainedIterable(final Iterable<? extends E>... ite
             public Iterator<E> iterator() {
                 return new LazyIteratorChain<E>() {
                     @Override
-                    protected Iterator<? extends E> nextIterator(int count) {
+                    protected Iterator<? extends E> nextIterator(final int count) {
                         if (count > iterables.length) {
                             return null;
                         }
@@ -324,7 +324,7 @@ public static <E> Iterable<E> loopingIterable(final Iterable<E> iterable) {
             public Iterator<E> iterator() {
                 return new LazyIteratorChain<E>() {
                     @Override
-                    protected Iterator<? extends E> nextIterator(int count) {
+                    protected Iterator<? extends E> nextIterator(final int count) {
                         if (IterableUtils.isEmpty(iterable)) {
                             return null;
                         }
@@ -546,6 +546,7 @@ public static <E> Iterable<E> zippingIterable(final Iterable<? extends E> first,
             @Override
             public Iterator<E> iterator() {
                 @SuppressWarnings("unchecked") // safe
+                final
                 Iterator<? extends E>[] iterators = new Iterator[others.length + 1];
                 iterators[0] = first.iterator();
                 for (int i = 0; i < others.length; i++) {
@@ -915,7 +916,7 @@ public static <O, R extends Collection<O>> List<R> partition(final Iterable<? ex
             throw new NullPointerException("Predicates must not be null.");
         }
 
-        for (Predicate<?> p : predicates) {
+        for (final Predicate<?> p : predicates) {
             if (p == null) {
                 throw new NullPointerException("Predicate must not be null.");
             }

src/main/java/org/apache/commons/collections4/IteratorUtils.java

@@ -433,7 +433,7 @@ public static <E> ResettableListIterator<E> arrayListIterator(final Object array
      * @throws IllegalArgumentException if max is negative
      * @since 4.1
      */
-    public static <E> BoundedIterator<E> boundedIterator(final Iterator<? extends E> iterator, long max) {
+    public static <E> BoundedIterator<E> boundedIterator(final Iterator<? extends E> iterator, final long max) {
         return boundedIterator(iterator, 0, max);
     }
 
@@ -455,7 +455,7 @@ public static <E> BoundedIterator<E> boundedIterator(final Iterator<? extends E>
      * @since 4.1
      */
     public static <E> BoundedIterator<E> boundedIterator(final Iterator<? extends E> iterator,
-                                                         long offset, long max) {
+                                                         final long offset, final long max) {
         return new BoundedIterator<>(iterator, offset, max);
     }
 
@@ -890,7 +890,7 @@ public static <E> Iterator<E> pushbackIterator(final Iterator<? extends E> itera
      * @throws IllegalArgumentException if offset is negative
      * @since 4.1
      */
-    public static <E> SkippingIterator<E> skippingIterator(final Iterator<E> iterator, long offset) {
+    public static <E> SkippingIterator<E> skippingIterator(final Iterator<E> iterator, final long offset) {
         return new SkippingIterator<>(iterator, offset);
     }
 

src/main/java/org/apache/commons/collections4/ListUtils.java

@@ -570,7 +570,7 @@ public static String longestCommonSubsequence(final CharSequence a, final CharSe
         }
         final List<Character> lcs = longestCommonSubsequence(new CharSequenceAsList( a ), new CharSequenceAsList( b ));
         final StringBuilder sb = new StringBuilder();
-        for ( Character ch : lcs ) {
+        for ( final Character ch : lcs ) {
           sb.append(ch);
         }
         return sb.toString();
@@ -614,7 +614,7 @@ public CharSequenceAsList(final CharSequence sequence) {
       }
 
       @Override
-      public Character get( int index ) {
+      public Character get( final int index ) {
         return Character.valueOf(sequence.charAt( index ));
       }
 

src/main/java/org/apache/commons/collections4/MapUtils.java

@@ -1798,7 +1798,7 @@ public static <K, V> IterableSortedMap<K, V> iterableSortedMap(final SortedMap<K
      * @param map a Map or null
      * @return the given map size or 0 if the map is null
      */
-    public static int size(Map<?, ?> map) {
+    public static int size(final Map<?, ?> map) {
         return map == null ? 0 : map.size();
     }
 

src/main/java/org/apache/commons/collections4/MultiMapUtils.java

@@ -127,7 +127,7 @@ public static <K, V> Collection<V> getCollection(final MultiValuedMap<K, V> map,
      */
     public static <K, V> List<V> getValuesAsList(final MultiValuedMap<K, V> map, final K key) {
         if (map != null) {
-            Collection<V> col = map.get(key);
+            final Collection<V> col = map.get(key);
             if (col instanceof List) {
                 return (List<V>) col;
             }
@@ -147,7 +147,7 @@ public static <K, V> List<V> getValuesAsList(final MultiValuedMap<K, V> map, fin
      */
     public static <K, V> Set<V> getValuesAsSet(final MultiValuedMap<K, V> map, final K key) {
         if (map != null) {
-            Collection<V> col = map.get(key);
+            final Collection<V> col = map.get(key);
             if (col instanceof Set) {
                 return (Set<V>) col;
             }
@@ -167,7 +167,7 @@ public static <K, V> Set<V> getValuesAsSet(final MultiValuedMap<K, V> map, final
      */
     public static <K, V> Bag<V> getValuesAsBag(final MultiValuedMap<K, V> map, final K key) {
         if (map != null) {
-            Collection<V> col = map.get(key);
+            final Collection<V> col = map.get(key);
             if (col instanceof Bag) {
                 return (Bag<V>) col;
             }

src/main/java/org/apache/commons/collections4/SetUtils.java

@@ -446,7 +446,7 @@ public static <E> SetView<E> union(final Set<? extends E> a, final Set<? extends
 
         return new SetView<E>() {
             @Override
-            public boolean contains(Object o) {
+            public boolean contains(final Object o) {
                 return a.contains(o) || b.contains(o);
             }
 
@@ -488,14 +488,14 @@ public static <E> SetView<E> difference(final Set<? extends E> a, final Set<? ex
 
         final Predicate<E> notContainedInB = new Predicate<E>() {
             @Override
-            public boolean evaluate(E object) {
+            public boolean evaluate(final E object) {
                 return !b.contains(object);
             }
         };
 
         return new SetView<E>() {
             @Override
-            public boolean contains(Object o) {
+            public boolean contains(final Object o) {
                 return a.contains(o) && !b.contains(o);
             }
 
@@ -526,14 +526,14 @@ public static <E> SetView<E> intersection(final Set<? extends E> a, final Set<?
 
         final Predicate<E> containedInB = new Predicate<E>() {
             @Override
-            public boolean evaluate(E object) {
+            public boolean evaluate(final E object) {
                 return b.contains(object);
             }
         };
 
         return new SetView<E>() {
             @Override
-            public boolean contains(Object o) {
+            public boolean contains(final Object o) {
                 return a.contains(o) && b.contains(o);
             }
 
@@ -570,7 +570,7 @@ public static <E> SetView<E> disjunction(final Set<? extends E> a, final Set<? e
 
         return new SetView<E>() {
             @Override
-            public boolean contains(Object o) {
+            public boolean contains(final Object o) {
                 return a.contains(o) ^ b.contains(o);
             }
 

src/main/java/org/apache/commons/collections4/bidimap/TreeBidiMap.java

@@ -1441,10 +1441,10 @@ private String doToString(final DataElement dataElement) {
     private void readObject(final ObjectInputStream stream) throws IOException, ClassNotFoundException{
         stream.defaultReadObject();
         rootNode = new Node[2];
-        int size = stream.readInt();
+        final int size = stream.readInt();
         for(int i = 0; i < size; i++){
-            K k =(K) stream.readObject();
-            V v =(V) stream.readObject();
+            final K k =(K) stream.readObject();
+            final V v =(V) stream.readObject();
             put(k, v);
         }
     }

src/main/java/org/apache/commons/collections4/collection/PredicatedCollection.java

@@ -256,7 +256,7 @@ public Builder<E> add(final E item) {
          */
         public Builder<E> addAll(final Collection<? extends E> items) {
             if (items != null) {
-                for (E item : items) {
+                for (final E item : items) {
                     add(item);
                 }
             }

src/main/java/org/apache/commons/collections4/iterators/PermutationIterator.java

@@ -82,7 +82,7 @@ public PermutationIterator(final Collection<? extends E> coll) {
         Arrays.fill(direction, false);
         int value = 1;
         objectMap = new HashMap<>();
-        for (E e : coll) {
+        for (final E e : coll) {
             objectMap.put(Integer.valueOf(value), e);
             keys[value - 1] = value;
             value++;
@@ -123,7 +123,7 @@ public List<E> next() {
             }
         }
         if (largestKey == -1) {
-            List<E> toReturn = nextPermutation;
+            final List<E> toReturn = nextPermutation;
             nextPermutation = null;
             return toReturn;
         }
@@ -133,7 +133,7 @@ public List<E> next() {
         final int tmpKey = keys[indexOfLargestMobileInteger];
         keys[indexOfLargestMobileInteger] = keys[indexOfLargestMobileInteger + offset];
         keys[indexOfLargestMobileInteger + offset] = tmpKey;
-        boolean tmpDirection = direction[indexOfLargestMobileInteger];
+        final boolean tmpDirection = direction[indexOfLargestMobileInteger];
         direction[indexOfLargestMobileInteger] = direction[indexOfLargestMobileInteger + offset];
         direction[indexOfLargestMobileInteger + offset] = tmpDirection;
 

src/main/java/org/apache/commons/collections4/keyvalue/AbstractKeyValue.java

@@ -53,7 +53,7 @@ public K getKey() {
         return key;
     }
 
-    protected K setKey(K key) {
+    protected K setKey(final K key) {
         final K old = this.key;
         this.key = key;
         return old;
@@ -69,7 +69,7 @@ public V getValue() {
         return value;
     }
 
-    protected V setValue(V value) {
+    protected V setValue(final V value) {
         final V old = this.value;
         this.value = value;
         return old;

src/main/java/org/apache/commons/collections4/list/SetUniqueList.java

@@ -261,7 +261,7 @@ public boolean removeAll(final Collection<?> coll) {
      */
     @Override
     public boolean retainAll(final Collection<?> coll) {
-        boolean result = set.retainAll(coll);
+        final boolean result = set.retainAll(coll);
         if (result == false) {
             return false;
         }

src/main/java/org/apache/commons/collections4/map/AbstractReferenceMap.java

@@ -1062,7 +1062,7 @@ protected void doReadObject(final ObjectInputStream in) throws IOException, Clas
      * @param type the type to check against.
      * @return true if keyType has the specified type
      */
-    protected boolean isKeyType(ReferenceStrength type) {
+    protected boolean isKeyType(final ReferenceStrength type) {
         return this.keyType == type;
     }
 }

src/main/java/org/apache/commons/collections4/map/MultiValueMap.java

@@ -429,7 +429,7 @@ public Iterator<Entry<K, V>> iterator() {
 
         return new LazyIteratorChain<Entry<K, V>>() {
             @Override
-            protected Iterator<? extends Entry<K, V>> nextIterator(int count) {
+            protected Iterator<? extends Entry<K, V>> nextIterator(final int count) {
                 if ( ! keyIterator.hasNext() ) {
                     return null;
                 }
@@ -447,7 +447,7 @@ public V getValue() {
                                 return input;
                             }
                             @Override
-                            public V setValue(V value) {
+                            public V setValue(final V value) {
                                 throw new UnsupportedOperationException();
                             }
                         };
@@ -566,7 +566,7 @@ public T create() {
             }
         }
 
-        private void readObject(ObjectInputStream is) throws IOException, ClassNotFoundException {
+        private void readObject(final ObjectInputStream is) throws IOException, ClassNotFoundException {
             is.defaultReadObject();
             // ensure that the de-serialized class is a Collection, COLLECTIONS-580
             if (clazz != null && !Collection.class.isAssignableFrom(clazz)) {