diff --git a/src/main/java/com/thealgorithms/conversions/HexaDecimalToBinary.java b/src/main/java/com/thealgorithms/conversions/HexaDecimalToBinary.java
index b6228488dc76..07acefc9fb14 100644
--- a/src/main/java/com/thealgorithms/conversions/HexaDecimalToBinary.java
+++ b/src/main/java/com/thealgorithms/conversions/HexaDecimalToBinary.java
@@ -1,43 +1,60 @@
package com.thealgorithms.conversions;
-// Hex [0-9],[A-F] -> Binary [0,1]
+/**
+ * Utility class for converting hexadecimal numbers to binary representation.
+ *
+ * A hexadecimal number consists of digits from {@code [0-9]} and {@code [A-F]} (case-insensitive),
+ * while binary representation uses only {@code [0, 1]}.
+ *
+ * This class provides methods to:
+ *
+ * - Convert a hexadecimal string to its binary string equivalent.
+ * - Ensure the binary output is padded to 8 bits (1 byte).
+ *
+ *
+ * Example:
+ *
+ * - {@code "A1"} → {@code "10100001"}
+ * - {@code "1"} → {@code "00000001"}
+ *
+ *
+ * This class assumes that the input hexadecimal string is valid.
+ */
public class HexaDecimalToBinary {
+
+ /**
+ * Converts a hexadecimal string to its binary string equivalent.
+ * The binary output is padded to a minimum of 8 bits (1 byte).
+ * Steps:
+ *
+ * - Convert the hexadecimal string to an integer.
+ * - Convert the integer to a binary string.
+ * - Pad the binary string to ensure it is at least 8 bits long.
+ * - Return the padded binary string.
+ *
+ *
+ * @param numHex the hexadecimal string (e.g., "A1", "7F")
+ * @throws NumberFormatException if the input string is not a valid hexadecimal number
+ * @return the binary string representation, padded to 8 bits (e.g., "10100001")
+ */
public String convert(String numHex) {
- // String a HexaDecimal:
int conHex = Integer.parseInt(numHex, 16);
- // Hex a Binary:
String binary = Integer.toBinaryString(conHex);
- // Output:
return completeDigits(binary);
}
+ /**
+ * Pads the binary string to ensure it is at least 8 bits long.
+ * If the binary string is shorter than 8 bits, it adds leading zeros.
+ *
+ * @param binNum the binary string to pad
+ * @return the padded binary string with a minimum length of 8
+ */
public String completeDigits(String binNum) {
- final int longBits = 8;
- for (int i = binNum.length(); i < longBits; i++) {
+ final int byteSize = 8;
+ while (binNum.length() < byteSize) {
binNum = "0" + binNum;
}
return binNum;
}
-
- public static void main(String[] args) {
- // Testing Numbers:
- String[] hexNums = {
- "1",
- "A1",
- "ef",
- "BA",
- "AA",
- "BB",
- "19",
- "01",
- "02",
- "03",
- "04",
- };
- HexaDecimalToBinary objConvert = new HexaDecimalToBinary();
-
- for (String num : hexNums) {
- System.out.println(num + " = " + objConvert.convert(num));
- }
- }
}
diff --git a/src/test/java/com/thealgorithms/conversions/HexaDecimalToBinaryTest.java b/src/test/java/com/thealgorithms/conversions/HexaDecimalToBinaryTest.java
index 72a0a0174a93..1426eab64d2c 100644
--- a/src/test/java/com/thealgorithms/conversions/HexaDecimalToBinaryTest.java
+++ b/src/test/java/com/thealgorithms/conversions/HexaDecimalToBinaryTest.java
@@ -2,14 +2,44 @@
import static org.junit.jupiter.api.Assertions.assertEquals;
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+/**
+ * Unit tests for the {@link EndianConverter} class.
+ */
public class HexaDecimalToBinaryTest {
- @Test
- public void testHexaDecimalToBinary() {
- HexaDecimalToBinary hexaDecimalToBinary = new HexaDecimalToBinary();
- assertEquals("1111111111111111111111111111111", hexaDecimalToBinary.convert("7fffffff"));
- assertEquals("101010111100110111101111", hexaDecimalToBinary.convert("abcdef"));
+ /**
+ * Parameterized test to validate the conversion from little-endian to big-endian.
+ * Hexadecimal values are passed as strings and converted to integers during the test.
+ */
+ @ParameterizedTest
+ @CsvSource({
+ "0x78563412, 0x12345678", "0x00000000, 0x00000000", "0x00000001, 0x01000000",
+ "0xFFFFFFFF, 0xFFFFFFFF", // -1 in two's complement
+ "0x0000007F, 0x7F000000" // Positive boundary case
+ })
+ public void
+ testLittleToBigEndian(String inputHex, String expectedHex) {
+ int input = (int) Long.parseLong(inputHex.substring(2), 16); // Convert hex string to int
+ int expected = (int) Long.parseLong(expectedHex.substring(2), 16); // Convert hex string to int
+ assertEquals(expected, EndianConverter.littleToBigEndian(input));
+ }
+
+ /**
+ * Parameterized test to validate the conversion from big-endian to little-endian.
+ */
+ @ParameterizedTest
+ @CsvSource({
+ "0x12345678, 0x78563412", "0x00000000, 0x00000000", "0x01000000, 0x00000001",
+ "0xFFFFFFFF, 0xFFFFFFFF", // -1 in two's complement
+ "0x7F000000, 0x0000007F" // Positive boundary case
+ })
+ public void
+ testBigToLittleEndian(String inputHex, String expectedHex) {
+ int input = (int) Long.parseLong(inputHex.substring(2), 16); // Convert hex string to int
+ int expected = (int) Long.parseLong(expectedHex.substring(2), 16); // Convert hex string to int
+ assertEquals(expected, EndianConverter.bigToLittleEndian(input));
}
}
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