Merge branch 'refs/heads/master' into refactor/DynamicArray

Author: Alex Klymenko

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

@@ -1,69 +1,69 @@
 package com.thealgorithms.conversions;
 
-import java.io.BufferedReader;
-import java.io.InputStreamReader;
 import java.util.ArrayList;
+import java.util.List;
 
 /**
+ *  Class that provides methods to convert a decimal number to a string representation
+ *  in any specified base between 2 and 36.
+ *
  * @author Varun Upadhyay (<a href="https://github.com/varunu28">...</a>)
  */
-// Driver Program
 public final class DecimalToAnyBase {
-    private DecimalToAnyBase() {
-    }
-
-    public static void main(String[] args) throws Exception {
-        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
-        System.out.println("Enter the decimal input below: ");
-        int decInput = Integer.parseInt(br.readLine());
-        System.out.println();
-
-        System.out.println("Enter the base below: ");
-        int base = Integer.parseInt(br.readLine());
-        System.out.println();
+    private static final int MIN_BASE = 2;
+    private static final int MAX_BASE = 36;
+    private static final char ZERO_CHAR = '0';
+    private static final char A_CHAR = 'A';
+    private static final int DIGIT_OFFSET = 10;
 
-        System.out.println("Decimal Input"
-            + " is: " + decInput);
-        System.out.println("Value of " + decInput + " in base " + base + " is: " + convertToAnyBase(decInput, base));
-
-        br.close();
+    private DecimalToAnyBase() {
     }
 
     /**
-     * This method produces a String value of any given input decimal in any
-     * base
+     * Converts a decimal number to a string representation in the specified base.
+     * For example, converting the decimal number 10 to base 2 would return "1010".
      *
-     * @param inp Decimal of which we need the value in base in String format
-     * @return string format of the converted value in the given base
+     * @param decimal the decimal number to convert
+     * @param base    the base to convert to (must be between {@value #MIN_BASE} and {@value #MAX_BASE})
+     * @return the string representation of the number in the specified base
+     * @throws IllegalArgumentException if the base is out of the supported range
      */
-    public static String convertToAnyBase(int inp, int base) {
-        ArrayList<Character> charArr = new ArrayList<>();
+    public static String convertToAnyBase(int decimal, int base) {
+        if (base < MIN_BASE || base > MAX_BASE) {
+            throw new IllegalArgumentException("Base must be between " + MIN_BASE + " and " + MAX_BASE);
+        }
 
-        while (inp > 0) {
-            charArr.add(reVal(inp % base));
-            inp /= base;
+        if (decimal == 0) {
+            return String.valueOf(ZERO_CHAR);
         }
 
-        StringBuilder str = new StringBuilder(charArr.size());
+        List<Character> digits = new ArrayList<>();
+        while (decimal > 0) {
+            digits.add(convertToChar(decimal % base));
+            decimal /= base;
+        }
 
-        for (Character ch : charArr) {
-            str.append(ch);
+        StringBuilder result = new StringBuilder(digits.size());
+        for (int i = digits.size() - 1; i >= 0; i--) {
+            result.append(digits.get(i));
         }
 
-        return str.reverse().toString();
+        return result.toString();
     }
 
     /**
-     * This method produces character value of the input integer and returns it
+     * Converts an integer value to its corresponding character in the specified base.
+     * This method is used to convert values from 0 to 35 into their appropriate character representation.
+     * For example, 0-9 are represented as '0'-'9', and 10-35 are represented as 'A'-'Z'.
      *
-     * @param num integer of which we need the character value of
-     * @return character value of input integer
+     * @param value the integer value to convert (should be less than the base value)
+     * @return the character representing the value in the specified base
      */
-    public static char reVal(int num) {
-        if (num >= 0 && num <= 9) {
-            return (char) (num + '0');
+    private static char convertToChar(int value) {
+        if (value >= 0 && value <= 9) {
+            return (char) (ZERO_CHAR + value);
         } else {
-            return (char) (num - 10 + 'A');
+            return (char) (A_CHAR + value - DIGIT_OFFSET);
         }
     }
 }

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

@@ -1,47 +1,42 @@
 package com.thealgorithms.conversions;
 
-import java.util.Scanner;
-
 /**
- * Converts any Octal Number to a Decimal Number
+ * Class for converting an octal number to a decimal number. Octal numbers are based on 8, using digits from 0 to 7.
  *
- * @author Zachary Jones
  */
 public final class OctalToDecimal {
+    private static final int OCTAL_BASE = 8;
+
     private OctalToDecimal() {
     }
 
     /**
-     * Main method
+     * Converts a given octal number (as a string) to its decimal representation.
+     * If the input is not a valid octal number (i.e., contains characters other than 0-7),
+     * the method throws an IllegalArgumentException.
      *
-     * @param args Command line arguments
+     * @param inputOctal The octal number as a string
+     * @return The decimal equivalent of the octal number
+     * @throws IllegalArgumentException if the input is not a valid octal number
      */
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        System.out.print("Octal Input: ");
-        String inputOctal = sc.nextLine();
-        int result = convertOctalToDecimal(inputOctal);
-        if (result != -1) {
-            System.out.println("Result convertOctalToDecimal : " + result);
+    public static int convertOctalToDecimal(String inputOctal) {
+        if (inputOctal == null || inputOctal.isEmpty()) {
+            throw new IllegalArgumentException("Input cannot be null or empty");
         }
-        sc.close();
-    }
 
-    /**
-     * This method converts an octal number to a decimal number.
-     *
-     * @param inputOctal The octal number
-     * @return The decimal number
-     */
-    public static int convertOctalToDecimal(String inputOctal) {
-        try {
-            // Actual conversion of Octal to Decimal:
-            return Integer.parseInt(inputOctal, 8);
-        } catch (NumberFormatException ne) {
-            // Printing a warning message if the input is not a valid octal
-            // number:
-            System.out.println("Invalid Input, Expecting octal number 0-7");
-            return -1;
+        int decimalValue = 0;
+
+        for (int i = 0; i < inputOctal.length(); i++) {
+            char currentChar = inputOctal.charAt(i);
+
+            if (currentChar < '0' || currentChar > '7') {
+                throw new IllegalArgumentException("Incorrect input: Expecting an octal number (digits 0-7)");
+            }
+
+            int currentDigit = currentChar - '0';
+            decimalValue = decimalValue * OCTAL_BASE + currentDigit;
         }
+
+        return decimalValue;
     }
 }

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

@@ -1,65 +1,61 @@
 package com.thealgorithms.conversions;
 
-import java.util.Scanner;
-
 /**
- * Converts any Octal Number to HexaDecimal
+ * Class for converting an Octal number to its Hexadecimal equivalent.
  *
  * @author Tanmay Joshi
  */
 public final class OctalToHexadecimal {
+    private static final int OCTAL_BASE = 8;
+    private static final int HEX_BASE = 16;
+    private static final String HEX_DIGITS = "0123456789ABCDEF";
+
     private OctalToHexadecimal() {
     }
 
     /**
-     * This method converts a Octal number to a decimal number
+     * Converts an Octal number (as a string) to its Decimal equivalent.
      *
-     * @param s The Octal Number
-     * @return The Decimal number
+     * @param octalNumber The Octal number as a string
+     * @return The Decimal equivalent of the Octal number
+     * @throws IllegalArgumentException if the input contains invalid octal digits
      */
-    public static int octToDec(String s) {
-        int i = 0;
-        for (int j = 0; j < s.length(); j++) {
-            char num = s.charAt(j);
-            num -= '0';
-            i *= 8;
-            i += num;
+    public static int octalToDecimal(String octalNumber) {
+        if (octalNumber == null || octalNumber.isEmpty()) {
+            throw new IllegalArgumentException("Input cannot be null or empty");
         }
-        return i;
+
+        int decimalValue = 0;
+        for (int i = 0; i < octalNumber.length(); i++) {
+            char currentChar = octalNumber.charAt(i);
+            if (currentChar < '0' || currentChar > '7') {
+                throw new IllegalArgumentException("Incorrect octal digit: " + currentChar);
+            }
+            int currentDigit = currentChar - '0';
+            decimalValue = decimalValue * OCTAL_BASE + currentDigit;
+        }
+
+        return decimalValue;
     }
 
     /**
-     * This method converts a Decimal number to a Hexadecimal number
+     * Converts a Decimal number to its Hexadecimal equivalent.
      *
-     * @param d The Decimal Number
-     * @return The Hexadecimal number
+     * @param decimalNumber The Decimal number
+     * @return The Hexadecimal equivalent of the Decimal number
      */
-    public static String decimalToHex(int d) {
-        String digits = "0123456789ABCDEF";
-        if (d <= 0) {
+    public static String decimalToHexadecimal(int decimalNumber) {
+        if (decimalNumber == 0) {
             return "0";
         }
-        String hex = "";
-        while (d > 0) {
-            int digit = d % 16;
-            hex = digits.charAt(digit) + hex;
-            d = d / 16;
-        }
-        return hex;
-    }
 
-    public static void main(String[] args) {
-        Scanner input = new Scanner(System.in);
-        System.out.print("Enter the Octal number: ");
-        // Take octal number as input from user in a string
-        String oct = input.next();
-
-        // Pass the octal number to function and get converted decimal form
-        int decimal = octToDec(oct);
+        StringBuilder hexValue = new StringBuilder();
+        while (decimalNumber > 0) {
+            int digit = decimalNumber % HEX_BASE;
+            hexValue.insert(0, HEX_DIGITS.charAt(digit));
+            decimalNumber /= HEX_BASE;
+        }
 
-        // Pass the decimal number to function and get converted Hex form of the number
-        String hex = decimalToHex(decimal);
-        System.out.println("The Hexadecimal equivalant is: " + hex);
-        input.close();
+        return hexValue.toString();
     }
 }

src/test/java/com/thealgorithms/conversions/DecimalToAnyBaseTest.java

@@ -0,0 +1,23 @@
+package com.thealgorithms.conversions;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+public class DecimalToAnyBaseTest {
+
+    @ParameterizedTest
+    @CsvSource({"0, 2, 0", "0, 16, 0", "0, 36, 0", "10, 2, 1010", "255, 16, FF", "100, 8, 144", "42, 2, 101010", "1234, 16, 4D2", "1234, 36, YA"})
+    void testConvertToAnyBase(int decimal, int base, String expected) {
+        assertEquals(expected, DecimalToAnyBase.convertToAnyBase(decimal, base));
+    }
+
+    @Test
+    void testBaseOutOfRange() {
+        assertThrows(IllegalArgumentException.class, () -> DecimalToAnyBase.convertToAnyBase(10, 1));
+        assertThrows(IllegalArgumentException.class, () -> DecimalToAnyBase.convertToAnyBase(10, 37));
+    }
+}

src/test/java/com/thealgorithms/conversions/OctalToDecimalTest.java

@@ -1,14 +1,21 @@
 package com.thealgorithms.conversions;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
 public class OctalToDecimalTest {
 
-    @Test
-    public void testOctalToDecimal() {
-        assertEquals(1465, OctalToDecimal.convertOctalToDecimal("2671"));
-        assertEquals(189, OctalToDecimal.convertOctalToDecimal("275"));
+    @ParameterizedTest
+    @CsvSource({"10, 8", "7, 7", "77, 63", "123, 83", "0, 0", "777, 511", "2671, 1465", "275, 189"})
+    void testConvertOctalToDecimal(String inputOctal, int expectedDecimal) {
+        Assertions.assertEquals(expectedDecimal, OctalToDecimal.convertOctalToDecimal(inputOctal));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"'', Input cannot be null or empty", "'8', Incorrect input: Expecting an octal number (digits 0-7)", "'19', Incorrect input: Expecting an octal number (digits 0-7)"})
+    void testIncorrectInput(String inputOctal, String expectedMessage) {
+        IllegalArgumentException exception = Assertions.assertThrows(IllegalArgumentException.class, () -> OctalToDecimal.convertOctalToDecimal(inputOctal));
+        Assertions.assertEquals(expectedMessage, exception.getMessage());
     }
 }

src/test/java/com/thealgorithms/conversions/OctalToHexadecimalTest.java

@@ -1,14 +1,23 @@
 package com.thealgorithms.conversions;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
 public class OctalToHexadecimalTest {
 
-    @Test
-    public void testOctalToHexadecimal() {
-        assertEquals("1EA", OctalToHexadecimal.decimalToHex(OctalToHexadecimal.octToDec("752")));
-        assertEquals("15E", OctalToHexadecimal.decimalToHex(OctalToHexadecimal.octToDec("536")));
+    @ParameterizedTest
+    @CsvSource({"0, 0", "7, 7", "10, 8", "17, F", "20, 10", "777, 1FF", "1234, 29C", "752, 1EA", "536, 15E"})
+    void testCorrectInputs(String inputOctal, String expectedHex) {
+        int decimal = OctalToHexadecimal.octalToDecimal(inputOctal);
+        String hex = OctalToHexadecimal.decimalToHexadecimal(decimal);
+        Assertions.assertEquals(expectedHex, hex);
+    }
+
+    @ParameterizedTest
+    @CsvSource({"'', Input cannot be null or empty", "'8', Incorrect octal digit: 8", "'19', Incorrect octal digit: 9"})
+    void testIncorrectInputs(String inputOctal, String expectedMessage) {
+        IllegalArgumentException exception = Assertions.assertThrows(IllegalArgumentException.class, () -> OctalToHexadecimal.octalToDecimal(inputOctal));
+        Assertions.assertEquals(expectedMessage, exception.getMessage());
     }
 }