diff --git a/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java b/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
index fdb91220b..c6af33a06 100644
--- a/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
+++ b/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
@@ -295,8 +295,8 @@ public class CharSequenceUtils {
             }
 
             // The real same check as in String.regionMatches():
-            char u1 = Character.toUpperCase(c1);
-            char u2 = Character.toUpperCase(c2);
+            final char u1 = Character.toUpperCase(c1);
+            final char u2 = Character.toUpperCase(c2);
             if (u1 != u2 && Character.toLowerCase(u1) != Character.toLowerCase(u2)) {
                 return false;
             }
diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 1ae2e38e4..5b8723016 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -6693,8 +6693,8 @@ public class StringUtils {
 
         // if recursing, this shouldn't be less than 0
         if (timeToLive < 0) {
-            Set<String> searchSet = new HashSet<>(Arrays.asList(searchList));
-            Set<String> replacementSet = new HashSet<>(Arrays.asList(replacementList));
+            final Set<String> searchSet = new HashSet<>(Arrays.asList(searchList));
+            final Set<String> replacementSet = new HashSet<>(Arrays.asList(replacementList));
             searchSet.retainAll(replacementSet);
             if (searchSet.size() > 0) {
                 throw new IllegalStateException("Aborting to protect against StackOverflowError - " +
@@ -8277,7 +8277,7 @@ public class StringUtils {
      * @return the stripped Strings, {@code null} if null array input
      */
     public static String[] stripAll(final String[] strs, final String stripChars) {
-        int strsLen = ArrayUtils.getLength(strs);
+        final int strsLen = ArrayUtils.getLength(strs);
         if (strsLen == 0) {
             return strs;
         }
diff --git a/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java b/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java
index 4856c32c3..56fda5556 100644
--- a/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java
+++ b/src/main/java/org/apache/commons/lang3/builder/ToStringStyle.java
@@ -627,7 +627,7 @@ public abstract class ToStringStyle implements Serializable {
         if (coll != null && !coll.isEmpty()) {
             buffer.append(arrayStart);
             int i = 0;
-            for (Object item : coll) {
+            for (final Object item : coll) {
                 appendDetail(buffer, fieldName, i++, item);
             }
             buffer.append(arrayEnd);
@@ -944,7 +944,7 @@ public abstract class ToStringStyle implements Serializable {
      * @param item the array item to add
      * @since 3.11
      */
-    protected void appendDetail(final StringBuffer buffer, final String fieldName, int i, final Object item) {
+    protected void appendDetail(final StringBuffer buffer, final String fieldName, final int i, final Object item) {
         if (i > 0) {
             buffer.append(arraySeparator);
         }
diff --git a/src/test/java/org/apache/commons/lang3/FunctionsTest.java b/src/test/java/org/apache/commons/lang3/FunctionsTest.java
index 798591294..cd0607de7 100644
--- a/src/test/java/org/apache/commons/lang3/FunctionsTest.java
+++ b/src/test/java/org/apache/commons/lang3/FunctionsTest.java
@@ -76,17 +76,17 @@ public class FunctionsTest {
             return true;
         }
 
-        static boolean testDouble(double value) throws SomeException {
+        static boolean testDouble(final double value) throws SomeException {
             throwOnOdd();
             return true;
         }
 
-        static boolean testInt(int value) throws SomeException {
+        static boolean testInt(final int value) throws SomeException {
             throwOnOdd();
             return true;
         }
 
-        static boolean testLong(long value) throws SomeException {
+        static boolean testLong(final long value) throws SomeException {
             throwOnOdd();
             return true;
         }
@@ -159,7 +159,7 @@ public class FunctionsTest {
             test(throwable);
         }
 
-        public Object test(Object input1, Object input2) throws Throwable {
+        public Object test(final Object input1, final Object input2) throws Throwable {
             test(throwable);
             return acceptedObject;
         }
@@ -225,41 +225,41 @@ public class FunctionsTest {
             return 0;
         }
 
-        public void testDouble(double i) throws Throwable {
+        public void testDouble(final double i) throws Throwable {
             test(throwable);
             acceptedPrimitiveObject1 = (P) ((Double) i);
         }
 
-        public double testDoubleDouble(double i, double j) throws Throwable {
+        public double testDoubleDouble(final double i, final double j) throws Throwable {
             test(throwable);
             acceptedPrimitiveObject1 = (P) ((Double) i);
             acceptedPrimitiveObject2 = (P) ((Double) j);
             return 3d;
         }
 
-        public void testInt(int i) throws Throwable {
+        public void testInt(final int i) throws Throwable {
             test(throwable);
             acceptedPrimitiveObject1 = (P) ((Integer) i);
         }
 
-        public void testLong(long i) throws Throwable {
+        public void testLong(final long i) throws Throwable {
             test(throwable);
             acceptedPrimitiveObject1 = (P) ((Long) i);
         }
 
-        public void testObjDouble(T object, double i) throws Throwable {
+        public void testObjDouble(final T object, final double i) throws Throwable {
             test(throwable);
             acceptedObject = object;
             acceptedPrimitiveObject1 = (P) ((Double) i);
         }
 
-        public void testObjInt(T object, int i) throws Throwable {
+        public void testObjInt(final T object, final int i) throws Throwable {
             test(throwable);
             acceptedObject = object;
             acceptedPrimitiveObject1 = (P) ((Integer) i);
         }
 
-        public void testObjLong(T object, long i) throws Throwable {
+        public void testObjLong(final T object, final long i) throws Throwable {
             test(throwable);
             acceptedObject = object;
             acceptedPrimitiveObject1 = (P) ((Long) i);
@@ -800,7 +800,7 @@ public class FunctionsTest {
         new Functions.FailableBiConsumer<Object, Object, Throwable>() {
 
             @Override
-            public void accept(Object object1, Object object2) throws Throwable {
+            public void accept(final Object object1, final Object object2) throws Throwable {
                 throw new IOException("test");
             }
         };
@@ -815,7 +815,7 @@ public class FunctionsTest {
         new Functions.FailableBiConsumer<String, String, IOException>() {
 
             @Override
-            public void accept(String object1, String object2) throws IOException {
+            public void accept(final String object1, final String object2) throws IOException {
                 throw new IOException("test");
 
             }
@@ -831,7 +831,7 @@ public class FunctionsTest {
         new Functions.FailableBiFunction<Object, Object, Object, Throwable>() {
 
             @Override
-            public Object apply(Object input1, Object input2) throws Throwable {
+            public Object apply(final Object input1, final Object input2) throws Throwable {
                 throw new IOException("test");
             }
         };
@@ -846,7 +846,7 @@ public class FunctionsTest {
         new Functions.FailableBiFunction<String, String, String, IOException>() {
 
             @Override
-            public String apply(String input1, String input2) throws IOException {
+            public String apply(final String input1, final String input2) throws IOException {
                 throw new IOException("test");
             }
         };
@@ -861,7 +861,7 @@ public class FunctionsTest {
         new Functions.FailableBiPredicate<Object, Object, Throwable>() {
 
             @Override
-            public boolean test(Object object1, Object object2) throws Throwable {
+            public boolean test(final Object object1, final Object object2) throws Throwable {
                 throw new IOException("test");
             }
         };
@@ -876,7 +876,7 @@ public class FunctionsTest {
         new Functions.FailableBiPredicate<String, String, IOException>() {
 
             @Override
-            public boolean test(String object1, String object2) throws IOException {
+            public boolean test(final String object1, final String object2) throws IOException {
                 throw new IOException("test");
             }
         };
@@ -921,7 +921,7 @@ public class FunctionsTest {
         new Functions.FailableConsumer<Object, Throwable>() {
 
             @Override
-            public void accept(Object object) throws Throwable {
+            public void accept(final Object object) throws Throwable {
                 throw new IOException("test");
 
             }
@@ -937,7 +937,7 @@ public class FunctionsTest {
         new Functions.FailableConsumer<String, IOException>() {
 
             @Override
-            public void accept(String object) throws IOException {
+            public void accept(final String object) throws IOException {
                 throw new IOException("test");
 
             }
@@ -953,7 +953,7 @@ public class FunctionsTest {
         new Functions.FailableFunction<Object, Object, Throwable>() {
 
             @Override
-            public Object apply(Object input) throws Throwable {
+            public Object apply(final Object input) throws Throwable {
                 throw new IOException("test");
             }
         };
@@ -968,7 +968,7 @@ public class FunctionsTest {
         new Functions.FailableFunction<String, String, IOException>() {
 
             @Override
-            public String apply(String input) throws IOException {
+            public String apply(final String input) throws IOException {
                 throw new IOException("test");
             }
         };
@@ -983,7 +983,7 @@ public class FunctionsTest {
         new Functions.FailablePredicate<Object, Throwable>() {
 
             @Override
-            public boolean test(Object object) throws Throwable {
+            public boolean test(final Object object) throws Throwable {
                 throw new IOException("test");
             }
         };
@@ -998,7 +998,7 @@ public class FunctionsTest {
         new Functions.FailablePredicate<String, IOException>() {
 
             @Override
-            public boolean test(String object) throws IOException {
+            public boolean test(final String object) throws IOException {
                 throw new IOException("test");
             }
         };
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index 622cad566..7c657d0f8 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -60,11 +60,11 @@ public class StringUtilsTest {
     static final String NON_TRIMMABLE;
 
     static {
-        StringBuilder ws = new StringBuilder();
-        StringBuilder nws = new StringBuilder();
+        final StringBuilder ws = new StringBuilder();
+        final StringBuilder nws = new StringBuilder();
         final String hs = String.valueOf(((char) 160));
-        StringBuilder tr = new StringBuilder();
-        StringBuilder ntr = new StringBuilder();
+        final StringBuilder tr = new StringBuilder();
+        final StringBuilder ntr = new StringBuilder();
         for (int i = 0; i < Character.MAX_VALUE; i++) {
             if (Character.isWhitespace((char) i)) {
                 ws.append(String.valueOf((char) i));
@@ -3310,25 +3310,25 @@ public class StringUtilsTest {
 
     @Test
     public void testGeorgianSample() {
-        char[] arrayI = new char[]{
+        final char[] arrayI = new char[]{
                 //Latin Small Letter dotless I
                 (char) 0x0131,
                 //Greek Capital Letter Theta
                 (char) 0x03F4
         };
-        char[] arrayJ = new char[]{
+        final char[] arrayJ = new char[]{
                 //Latin Capital Letter I with dot above
                 (char) 0x0130,
                 //Greek Theta Symbol
                 (char) 0x03D1
         };
-        for (char i : arrayI) {
-            for (char j : arrayJ) {
-                String si = String.valueOf(i);
-                String sj = String.valueOf(j);
-                boolean res1 = si.equalsIgnoreCase(sj);
-                CharSequence ci = new StringBuilder(si);
-                CharSequence cj = new StringBuilder(sj);
+        for (final char i : arrayI) {
+            for (final char j : arrayJ) {
+                final String si = String.valueOf(i);
+                final String sj = String.valueOf(j);
+                final boolean res1 = si.equalsIgnoreCase(sj);
+                final CharSequence ci = new StringBuilder(si);
+                final CharSequence cj = new StringBuilder(sj);
                 boolean res2 = StringUtils.startsWithIgnoreCase(ci, cj);
                 assertEquals(res1, res2, "si : " + si + " sj : " + sj);
                 res2 = StringUtils.endsWithIgnoreCase(ci, cj);
diff --git a/src/test/java/org/apache/commons/lang3/builder/JsonToStringStyleTest.java b/src/test/java/org/apache/commons/lang3/builder/JsonToStringStyleTest.java
index 623ddb90a..23895118a 100644
--- a/src/test/java/org/apache/commons/lang3/builder/JsonToStringStyleTest.java
+++ b/src/test/java/org/apache/commons/lang3/builder/JsonToStringStyleTest.java
@@ -186,8 +186,8 @@ public class JsonToStringStyleTest {
 
     @Test
     public void testList() {
-        Student student = new Student();
-        ArrayList<Hobby> objects = new ArrayList<>();
+        final Student student = new Student();
+        final ArrayList<Hobby> objects = new ArrayList<>();
 
         objects.add(Hobby.BOOK);
         objects.add(Hobby.SPORT);
@@ -204,8 +204,8 @@ public class JsonToStringStyleTest {
 
     @Test
     public void testArrayEnum() {
-        Teacher teacher = new Teacher();
-        Hobby[] hobbies = new Hobby[3];
+        final Teacher teacher = new Teacher();
+        final Hobby[] hobbies = new Hobby[3];
         hobbies[0] = Hobby.BOOK;
         hobbies[1] = Hobby.SPORT;
         hobbies[2] = Hobby.MUSIC;
@@ -221,30 +221,30 @@ public class JsonToStringStyleTest {
 
     @Test
     public void testCombineListAndEnum() {
-        Teacher teacher = new Teacher();
+        final Teacher teacher = new Teacher();
 
-        Hobby[] teacherHobbies = new Hobby[3];
+        final Hobby[] teacherHobbies = new Hobby[3];
         teacherHobbies[0] = Hobby.BOOK;
         teacherHobbies[1] = Hobby.SPORT;
         teacherHobbies[2] = Hobby.MUSIC;
 
         teacher.setHobbies(teacherHobbies);
 
-        Student john = new Student();
+        final Student john = new Student();
         john.setHobbies(Arrays.asList(Hobby.BOOK, Hobby.MUSIC));
 
-        Student alice = new Student();
+        final Student alice = new Student();
         alice.setHobbies(new ArrayList<>());
 
-        Student bob = new Student();
+        final Student bob = new Student();
         bob.setHobbies(Collections.singletonList(Hobby.BOOK));
 
-        ArrayList<Student> students = new ArrayList<>();
+        final ArrayList<Student> students = new ArrayList<>();
         students.add(john);
         students.add(alice);
         students.add(bob);
 
-        AcademyClass academyClass = new AcademyClass();
+        final AcademyClass academyClass = new AcademyClass();
         academyClass.setStudents(students);
         academyClass.setTeacher(teacher);
 
@@ -564,7 +564,7 @@ public class JsonToStringStyleTest {
             return hobbies;
         }
 
-        public void setHobbies(List<Hobby> hobbies) {
+        public void setHobbies(final List<Hobby> hobbies) {
             this.hobbies = hobbies;
         }
 
@@ -581,7 +581,7 @@ public class JsonToStringStyleTest {
             return hobbies;
         }
 
-        public void setHobbies(Hobby[] hobbies) {
+        public void setHobbies(final Hobby[] hobbies) {
             this.hobbies = hobbies;
         }
 
@@ -595,11 +595,11 @@ public class JsonToStringStyleTest {
         Teacher teacher;
         List<Student> students;
 
-        public void setTeacher(Teacher teacher) {
+        public void setTeacher(final Teacher teacher) {
             this.teacher = teacher;
         }
 
-        public void setStudents(List<Student> students) {
+        public void setStudents(final List<Student> students) {
             this.students = students;
         }
 
diff --git a/src/test/java/org/apache/commons/lang3/concurrent/LocksTest.java b/src/test/java/org/apache/commons/lang3/concurrent/LocksTest.java
index 461bb539e..2d577ecdb 100644
--- a/src/test/java/org/apache/commons/lang3/concurrent/LocksTest.java
+++ b/src/test/java/org/apache/commons/lang3/concurrent/LocksTest.java
@@ -44,7 +44,7 @@ public class LocksTest {
         runTest(DELAY, true, l -> assertTrue(l >= NUMBER_OF_THREADS*DELAY));
     }
 
-    private void runTest(long delay, boolean exclusiveLock, LongConsumer runTimeCheck) throws InterruptedException {
+    private void runTest(final long delay, final boolean exclusiveLock, final LongConsumer runTimeCheck) throws InterruptedException {
         final boolean[] booleanValues = new boolean[10];
         final Lock<boolean[]> lock = Locks.lock(booleanValues);
         final boolean[] runningValues = new boolean[10];
@@ -78,13 +78,13 @@ public class LocksTest {
         runTimeCheck.accept(endTime-startTime);
     }
 
-    protected void modify(boolean[] booleanArray, int offset, boolean value) {
+    protected void modify(final boolean[] booleanArray, final int offset, final boolean value) {
         synchronized(booleanArray) {
             booleanArray[offset] = value;
         }
     }
 
-    protected boolean someValueIsTrue(boolean[] booleanArray) {
+    protected boolean someValueIsTrue(final boolean[] booleanArray) {
         synchronized(booleanArray) {
             for (int i = 0;  i < booleanArray.length;  i++) {
                 if (booleanArray[i]) {