style: enable ConstantName in checkstyle

checkstyle.xml

@@ -108,7 +108,7 @@
 
     <!-- Checks for Naming Conventions.                  -->
     <!-- See https://checkstyle.org/checks/naming/index.html -->
-    <!-- TODO <module name="ConstantName"/> -->
+    <module name="ConstantName"/>
     <!-- TODO <module name="LocalFinalVariableName"/> -->
     <!-- TODO <module name="LocalVariableName"/> -->
     <!-- TODO <module name="MemberName"/> -->

src/main/java/com/thealgorithms/backtracking/KnightsTour.java

@@ -26,8 +26,8 @@
  */
 public class KnightsTour {
 
-    private static final int base = 12;
-    private static final int[][] moves = {
+    private static final int BASE = 12;
+    private static final int[][] MOVES = {
         {1, -2},
         {2, -1},
         {2, 1},
@@ -41,19 +41,19 @@ public class KnightsTour {
     private static int total; // total squares in chess
 
     public static void main(String[] args) {
-        grid = new int[base][base];
-        total = (base - 4) * (base - 4);
+        grid = new int[BASE][BASE];
+        total = (BASE - 4) * (BASE - 4);
 
-        for (int r = 0; r < base; r++) {
-            for (int c = 0; c < base; c++) {
-                if (r < 2 || r > base - 3 || c < 2 || c > base - 3) {
+        for (int r = 0; r < BASE; r++) {
+            for (int c = 0; c < BASE; c++) {
+                if (r < 2 || r > BASE - 3 || c < 2 || c > BASE - 3) {
                     grid[r][c] = -1;
                 }
             }
         }
 
-        int row = 2 + (int) (Math.random() * (base - 4));
-        int col = 2 + (int) (Math.random() * (base - 4));
+        int row = 2 + (int) (Math.random() * (BASE - 4));
+        int col = 2 + (int) (Math.random() * (BASE - 4));
 
         grid[row][col] = 1;
 
@@ -95,7 +95,7 @@ private static boolean solve(int row, int column, int count) {
     private static List<int[]> neighbors(int row, int column) {
         List<int[]> neighbour = new ArrayList<>();
 
-        for (int[] m : moves) {
+        for (int[] m : MOVES) {
             int x = m[0];
             int y = m[1];
             if (grid[row + y][column + x] == 0) {
@@ -109,7 +109,7 @@ private static List<int[]> neighbors(int row, int column) {
     // Returns the total count of neighbors
     private static int countNeighbors(int row, int column) {
         int num = 0;
-        for (int[] m : moves) {
+        for (int[] m : MOVES) {
             if (grid[row + m[1]][column + m[0]] == 0) {
                 num++;
             }

src/main/java/com/thealgorithms/ciphers/Polybius.java

@@ -15,7 +15,7 @@
  */
 public class Polybius {
 
-    private static final char[][] key = {
+    private static final char[][] KEY = {
         //         0    1    2    3    4
         /* 0 */ {'A', 'B', 'C', 'D', 'E'},
         /* 1 */ {'F', 'G', 'H', 'I', 'J'},
@@ -26,9 +26,9 @@ public class Polybius {
 
     private static String findLocationByCharacter(final char character) {
         final StringBuilder location = new StringBuilder();
-        for (int i = 0; i < key.length; i++) {
-            for (int j = 0; j < key[i].length; j++) {
-                if (character == key[i][j]) {
+        for (int i = 0; i < KEY.length; i++) {
+            for (int j = 0; j < KEY[i].length; j++) {
+                if (character == KEY[i][j]) {
                     location.append(i).append(j);
                     break;
                 }
@@ -53,7 +53,7 @@ public static String decrypt(final String ciphertext) {
         for (int i = 0; i < chars.length; i += 2) {
             int pozitionX = Character.getNumericValue(chars[i]);
             int pozitionY = Character.getNumericValue(chars[i + 1]);
-            plaintext.append(key[pozitionX][pozitionY]);
+            plaintext.append(KEY[pozitionX][pozitionY]);
         }
         return plaintext.toString();
     }

src/main/java/com/thealgorithms/conversions/DecimalToHexaDecimal.java

@@ -3,10 +3,10 @@
 // hex = [0 - 9] -> [A - F]
 class DecimalToHexaDecimal {
 
-    private static final int sizeOfIntInHalfBytes = 8;
-    private static final int numberOfBitsInAHalfByte = 4;
-    private static final int halfByte = 0x0F;
-    private static final char[] hexDigits = {
+    private static final int SIZE_OF_INT_IN_HALF_BYTES = 8;
+    private static final int NUMBER_OF_BITS_IN_HALF_BYTE = 4;
+    private static final int HALF_BYTE = 0x0F;
+    private static final char[] HEX_DIGITS = {
         '0',
         '1',
         '2',
@@ -27,12 +27,12 @@ class DecimalToHexaDecimal {
 
     // Returns the hex value of the dec entered in the parameter.
     public static String decToHex(int dec) {
-        StringBuilder hexBuilder = new StringBuilder(sizeOfIntInHalfBytes);
-        hexBuilder.setLength(sizeOfIntInHalfBytes);
-        for (int i = sizeOfIntInHalfBytes - 1; i >= 0; --i) {
-            int j = dec & halfByte;
-            hexBuilder.setCharAt(i, hexDigits[j]);
-            dec >>= numberOfBitsInAHalfByte;
+        StringBuilder hexBuilder = new StringBuilder(SIZE_OF_INT_IN_HALF_BYTES);
+        hexBuilder.setLength(SIZE_OF_INT_IN_HALF_BYTES);
+        for (int i = SIZE_OF_INT_IN_HALF_BYTES - 1; i >= 0; --i) {
+            int j = dec & HALF_BYTE;
+            hexBuilder.setCharAt(i, HEX_DIGITS[j]);
+            dec >>= NUMBER_OF_BITS_IN_HALF_BYTE;
         }
         return hexBuilder.toString().toLowerCase();
     }

src/main/java/com/thealgorithms/conversions/IntegerToRoman.java

@@ -9,7 +9,7 @@
  */
 public class IntegerToRoman {
 
-    private static final int[] allArabianRomanNumbers = new int[] {
+    private static final int[] ALL_ROMAN_NUMBERS_IN_ARABIC = new int[] {
         1000,
         900,
         500,
@@ -24,7 +24,7 @@ public class IntegerToRoman {
         4,
         1,
     };
-    private static final String[] allRomanNumbers = new String[] {
+    private static final String[] ALL_ROMAN_NUMBERS = new String[] {
         "M",
         "CM",
         "D",
@@ -48,13 +48,13 @@ public static String integerToRoman(int num) {
 
         StringBuilder builder = new StringBuilder();
 
-        for (int a = 0; a < allArabianRomanNumbers.length; a++) {
-            int times = num / allArabianRomanNumbers[a];
+        for (int a = 0; a < ALL_ROMAN_NUMBERS_IN_ARABIC.length; a++) {
+            int times = num / ALL_ROMAN_NUMBERS_IN_ARABIC[a];
             for (int b = 0; b < times; b++) {
-                builder.append(allRomanNumbers[a]);
+                builder.append(ALL_ROMAN_NUMBERS[a]);
             }
 
-            num -= times * allArabianRomanNumbers[a];
+            num -= times * ALL_ROMAN_NUMBERS_IN_ARABIC[a];
         }
 
         return builder.toString();

src/main/java/com/thealgorithms/conversions/RomanToInteger.java

@@ -4,9 +4,7 @@
 
 public class RomanToInteger {
 
-    private static final Map<Character, Integer> map = new HashMap<>() {
-        private static final long serialVersionUID = 87605733047260530L;
-
+    private static final Map<Character, Integer> ROMAN_TO_INT = new HashMap<>() {
         {
             put('I', 1);
             put('V', 5);
@@ -38,10 +36,10 @@ public static int romanToInt(String A) {
 
             if (prev != ' ') {
                 // checking current Number greater then previous or not
-                newPrev = map.get(prev) > newPrev ? map.get(prev) : newPrev;
+                newPrev = ROMAN_TO_INT.get(prev) > newPrev ? ROMAN_TO_INT.get(prev) : newPrev;
             }
 
-            int currentNum = map.get(c);
+            int currentNum = ROMAN_TO_INT.get(c);
 
             // if current number greater then prev max previous then add
             if (currentNum >= newPrev) {

src/main/java/com/thealgorithms/datastructures/trees/LCA.java

@@ -5,14 +5,14 @@
 
 public class LCA {
 
-    private static final Scanner scanner = new Scanner(System.in);
+    private static final Scanner SCANNER = new Scanner(System.in);
 
     public static void main(String[] args) {
         // The adjacency list representation of a tree:
         ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
 
         // v is the number of vertices and e is the number of edges
-        int v = scanner.nextInt(), e = v - 1;
+        int v = SCANNER.nextInt(), e = v - 1;
 
         for (int i = 0; i < v; i++) {
             adj.add(new ArrayList<Integer>());
@@ -21,8 +21,8 @@ public static void main(String[] args) {
         // Storing the given tree as an adjacency list
         int to, from;
         for (int i = 0; i < e; i++) {
-            to = scanner.nextInt();
-            from = scanner.nextInt();
+            to = SCANNER.nextInt();
+            from = SCANNER.nextInt();
 
             adj.get(to).add(from);
             adj.get(from).add(to);
@@ -38,7 +38,7 @@ public static void main(String[] args) {
         dfs(adj, 0, -1, parent, depth);
 
         // Inputting the two vertices whose LCA is to be calculated
-        int v1 = scanner.nextInt(), v2 = scanner.nextInt();
+        int v1 = SCANNER.nextInt(), v2 = SCANNER.nextInt();
 
         // Outputting the LCA
         System.out.println(getLCA(v1, v2, depth, parent));

src/main/java/com/thealgorithms/dynamicprogramming/Fibonacci.java

@@ -9,7 +9,7 @@
  */
 public class Fibonacci {
 
-    private static final Map<Integer, Integer> map = new HashMap<>();
+    private static final Map<Integer, Integer> CACHE = new HashMap<>();
 
     public static void main(String[] args) {
         // Methods all returning [0, 1, 1, 2, 3, 5, ...] for n = [0, 1, 2, 3, 4, 5, ...]
@@ -30,8 +30,8 @@ public static void main(String[] args) {
      * Outputs the nth fibonacci number
      */
     public static int fibMemo(int n) {
-        if (map.containsKey(n)) {
-            return map.get(n);
+        if (CACHE.containsKey(n)) {
+            return CACHE.get(n);
         }
 
         int f;
@@ -40,7 +40,7 @@ public static int fibMemo(int n) {
             f = n;
         } else {
             f = fibMemo(n - 1) + fibMemo(n - 2);
-            map.put(n, f);
+            CACHE.put(n, f);
         }
         return f;
     }

src/main/java/com/thealgorithms/dynamicprogramming/MatrixChainMultiplication.java

@@ -6,8 +6,8 @@
 
 public class MatrixChainMultiplication {
 
-    private static final Scanner scan = new Scanner(System.in);
-    private static final ArrayList<Matrix> mArray = new ArrayList<>();
+    private static final Scanner SCANNER = new Scanner(System.in);
+    private static final ArrayList<Matrix> MATRICES = new ArrayList<>();
     private static int size;
     private static int[][] m;
     private static int[][] s;
@@ -24,14 +24,14 @@ public static void main(String[] args) {
             int row = Integer.parseInt(mSize[1]);
 
             Matrix matrix = new Matrix(count, col, row);
-            mArray.add(matrix);
+            MATRICES.add(matrix);
             count++;
         }
-        for (Matrix m : mArray) {
+        for (Matrix m : MATRICES) {
             System.out.format("A(%d)  =  %2d  x  %2d%n", m.count(), m.col(), m.row());
         }
 
-        size = mArray.size();
+        size = MATRICES.size();
         m = new int[size + 1][size + 1];
         s = new int[size + 1][size + 1];
         p = new int[size + 1];
@@ -42,7 +42,7 @@ public static void main(String[] args) {
         }
 
         for (int i = 0; i < p.length; i++) {
-            p[i] = i == 0 ? mArray.get(i).col() : mArray.get(i - 1).row();
+            p[i] = i == 0 ? MATRICES.get(i).col() : MATRICES.get(i - 1).row();
         }
 
         matrixChainOrder();
@@ -109,7 +109,7 @@ private static void matrixChainOrder() {
 
     private static String[] input(String string) {
         System.out.print(string);
-        return (scan.nextLine().split(" "));
+        return (SCANNER.nextLine().split(" "));
     }
 }
 

src/main/java/com/thealgorithms/maths/FindKthNumber.java

@@ -8,7 +8,7 @@
  */
 public class FindKthNumber {
 
-    private static final Random random = new Random();
+    private static final Random RANDOM = new Random();
 
     public static void main(String[] args) {
         /* generate an array with random size and random elements */
@@ -29,11 +29,11 @@ public static void main(String[] args) {
     }
 
     private static int[] generateArray(int capacity) {
-        int size = random.nextInt(capacity) + 1;
+        int size = RANDOM.nextInt(capacity) + 1;
         int[] array = new int[size];
 
         for (int i = 0; i < size; i++) {
-            array[i] = random.nextInt() % 100;
+            array[i] = RANDOM.nextInt() % 100;
         }
         return array;
     }

src/main/java/com/thealgorithms/matrixexponentiation/Fibonacci.java

@@ -10,10 +10,10 @@
 public class Fibonacci {
 
     // Exponentiation matrix for Fibonacci sequence
-    private static final int[][] fibMatrix = {{1, 1}, {1, 0}};
-    private static final int[][] identityMatrix = {{1, 0}, {0, 1}};
+    private static final int[][] FIB_MATRIX = {{1, 1}, {1, 0}};
+    private static final int[][] IDENTITY_MATRIX = {{1, 0}, {0, 1}};
     // First 2 fibonacci numbers
-    private static final int[][] baseFibNumbers = {{1}, {0}};
+    private static final int[][] BASE_FIB_NUMBERS = {{1}, {0}};
 
     /**
      * Performs multiplication of 2 matrices
@@ -53,14 +53,14 @@ private static int[][] matrixMultiplication(int[][] matrix1, int[][] matrix2) {
      */
     public static int[][] fib(int n) {
         if (n == 0) {
-            return Fibonacci.identityMatrix;
+            return Fibonacci.IDENTITY_MATRIX;
         } else {
             int[][] cachedResult = fib(n / 2);
             int[][] matrixExpResult = matrixMultiplication(cachedResult, cachedResult);
             if (n % 2 == 0) {
                 return matrixExpResult;
             } else {
-                return matrixMultiplication(Fibonacci.fibMatrix, matrixExpResult);
+                return matrixMultiplication(Fibonacci.FIB_MATRIX, matrixExpResult);
             }
         }
     }
@@ -69,7 +69,7 @@ public static void main(String[] args) {
         // Returns [0, 1, 1, 2, 3, 5 ..] for n = [0, 1, 2, 3, 4, 5.. ]
         Scanner sc = new Scanner(System.in);
         int n = sc.nextInt();
-        int[][] result = matrixMultiplication(fib(n), baseFibNumbers);
+        int[][] result = matrixMultiplication(fib(n), BASE_FIB_NUMBERS);
         System.out.println("Fib(" + n + ") = " + result[1][0]);
         sc.close();
     }

src/main/java/com/thealgorithms/others/Conway.java

@@ -13,7 +13,7 @@ public class Conway {
      *1s, two 2s, one 1" or 312211. https://en.wikipedia.org/wiki/Look-and-say_sequence
      * */
 
-    private static final StringBuilder builder = new StringBuilder();
+    private static final StringBuilder BUILDER = new StringBuilder();
 
     protected static List<String> generateList(String originalString, int maxIteration) {
         List<String> numbers = new ArrayList<>();
@@ -25,9 +25,9 @@ protected static List<String> generateList(String originalString, int maxIterati
     }
 
     public static String generateNextElement(String originalString) {
-        builder.setLength(0);
+        BUILDER.setLength(0);
         String[] stp = originalString.split("(?<=(.))(?!\\1)");
-        Arrays.stream(stp).forEach(s -> builder.append(s.length()).append(s.charAt(0)));
-        return builder.toString();
+        Arrays.stream(stp).forEach(s -> BUILDER.append(s.length()).append(s.charAt(0)));
+        return BUILDER.toString();
     }
 }