Merge branch 'master' into refactor/binary_to_decimal

Author: siriak

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

@@ -1,60 +1,63 @@
 package com.thealgorithms.conversions;
 
 import java.util.HashMap;
-import java.util.Scanner;
+import java.util.Map;
 
 /**
  * Converts any Binary Number to a Hexadecimal Number
  *
  * @author Nishita Aggarwal
  */
 public final class BinaryToHexadecimal {
+    private static final int BITS_IN_HEX_DIGIT = 4;
+    private static final int BASE_BINARY = 2;
+    private static final int BASE_DECIMAL = 10;
+    private static final int HEX_START_DECIMAL = 10;
+    private static final int HEX_END_DECIMAL = 15;
+
     private BinaryToHexadecimal() {
     }
 
     /**
-     * This method converts a binary number to a hexadecimal number.
+     * Converts a binary number to a hexadecimal number.
      *
-     * @param binary The binary number
-     * @return The hexadecimal number
+     * @param binary The binary number to convert.
+     * @return The hexadecimal representation of the binary number.
+     * @throws IllegalArgumentException If the binary number contains digits other than 0 and 1.
      */
-    static String binToHex(int binary) {
-        // hm to store hexadecimal codes for binary numbers within the range: 0000 to 1111 i.e. for
-        // decimal numbers 0 to 15
-        HashMap<Integer, String> hm = new HashMap<>();
-        // String to store hexadecimal code
-        String hex = "";
-        int i;
-        for (i = 0; i < 10; i++) {
-            hm.put(i, String.valueOf(i));
-        }
-        for (i = 10; i < 16; i++) {
-            hm.put(i, String.valueOf((char) ('A' + i - 10)));
-        }
-        int currbit;
+    public static String binToHex(int binary) {
+        Map<Integer, String> hexMap = initializeHexMap();
+        StringBuilder hex = new StringBuilder();
+
         while (binary != 0) {
-            int code4 = 0; // to store decimal equivalent of number formed by 4 decimal digits
-            for (i = 0; i < 4; i++) {
-                currbit = binary % 10;
-                binary = binary / 10;
-                code4 += currbit * (int) Math.pow(2, i);
+            int decimalValue = 0;
+            for (int i = 0; i < BITS_IN_HEX_DIGIT; i++) {
+                int currentBit = binary % BASE_DECIMAL;
+                if (currentBit > 1) {
+                    throw new IllegalArgumentException("Incorrect binary digit: " + currentBit);
+                }
+                binary /= BASE_DECIMAL;
+                decimalValue += (int) (currentBit * Math.pow(BASE_BINARY, i));
             }
-            hex = hm.get(code4) + hex;
+            hex.insert(0, hexMap.get(decimalValue));
         }
-        return hex;
+
+        return !hex.isEmpty() ? hex.toString() : "0";
     }
 
     /**
-     * Main method
+     * Initializes the hexadecimal map with decimal to hexadecimal mappings.
      *
-     * @param args Command line arguments
+     * @return The initialized map containing mappings from decimal numbers to hexadecimal digits.
      */
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        System.out.println("Enter binary number:");
-        int binary = sc.nextInt();
-        String hex = binToHex(binary);
-        System.out.println("Hexadecimal Code:" + hex);
-        sc.close();
+    private static Map<Integer, String> initializeHexMap() {
+        Map<Integer, String> hexMap = new HashMap<>();
+        for (int i = 0; i < BASE_DECIMAL; i++) {
+            hexMap.put(i, String.valueOf(i));
+        }
+        for (int i = HEX_START_DECIMAL; i <= HEX_END_DECIMAL; i++) {
+            hexMap.put(i, String.valueOf((char) ('A' + i - HEX_START_DECIMAL)));
+        }
+        return hexMap;
     }
 }

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

@@ -1,38 +1,38 @@
 package com.thealgorithms.conversions;
 
-import java.util.Scanner;
-
 /**
  * This class converts Decimal numbers to Octal Numbers
  */
 public final class DecimalToOctal {
+    private static final int OCTAL_BASE = 8;
+    private static final int INITIAL_OCTAL_VALUE = 0;
+    private static final int INITIAL_PLACE_VALUE = 1;
+
     private DecimalToOctal() {
     }
 
     /**
-     * Main Method
+     * Converts a decimal number to its octal equivalent.
      *
-     * @param args Command line Arguments
+     * @param decimal The decimal number to convert.
+     * @return The octal equivalent as an integer.
+     * @throws IllegalArgumentException if the decimal number is negative.
      */
+    public static int convertToOctal(int decimal) {
+        if (decimal < 0) {
+            throw new IllegalArgumentException("Decimal number cannot be negative.");
+        }
+
+        int octal = INITIAL_OCTAL_VALUE;
+        int placeValue = INITIAL_PLACE_VALUE;
 
-    // enter in a decimal value to get Octal output
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        int n;
-        int k;
-        int d;
-        int s = 0;
-        int c = 0;
-        System.out.print("Decimal number: ");
-        n = sc.nextInt();
-        k = n;
-        while (k != 0) {
-            d = k % 8;
-            s += d * (int) Math.pow(10, c++);
-            k /= 8;
+        while (decimal != 0) {
+            int remainder = decimal % OCTAL_BASE;
+            octal += remainder * placeValue;
+            decimal /= OCTAL_BASE;
+            placeValue *= 10;
         }
 
-        System.out.println("Octal equivalent:" + s);
-        sc.close();
+        return octal;
     }
 }

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

@@ -1,14 +1,22 @@
 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 BinaryToHexadecimalTest {
 
-    @Test
-    public void testBinaryToHexadecimal() {
-        assertEquals("6A", BinaryToHexadecimal.binToHex(1101010));
-        assertEquals("C", BinaryToHexadecimal.binToHex(1100));
+    @ParameterizedTest
+    @CsvSource({"0, 0", "1, 1", "10, 2", "1111, F", "1101010, 6A", "1100, C"})
+    void testBinToHex(int binary, String expectedHex) {
+        assertEquals(expectedHex, BinaryToHexadecimal.binToHex(binary));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"2", "1234", "11112"})
+    void testInvalidBinaryInput(int binary) {
+        assertThrows(IllegalArgumentException.class, () -> BinaryToHexadecimal.binToHex(binary));
     }
 }

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

@@ -0,0 +1,21 @@
+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;
+
+class DecimalToOctalTest {
+    @ParameterizedTest
+    @CsvSource({"0, 0", "7, 7", "8, 10", "10, 12", "64, 100", "83, 123", "7026, 15562"})
+    void testConvertToOctal(int decimal, int expectedOctal) {
+        assertEquals(expectedOctal, DecimalToOctal.convertToOctal(decimal));
+    }
+
+    @Test
+    void testConvertToOctalNegativeNumber() {
+        assertThrows(IllegalArgumentException.class, () -> DecimalToOctal.convertToOctal(-10));
+    }
+}