From 25b6aebe45795468f365ef9449525fcf258faffc Mon Sep 17 00:00:00 2001 From: Alex Klymenko Date: Sat, 17 Aug 2024 20:58:50 +0200 Subject: [PATCH] refactor: `DecimalToHexadecimal` (#5337) --- .../conversions/DecimalToHexaDecimal.java | 51 ------------------- .../conversions/DecimalToHexadecimal.java | 42 +++++++++++++++ .../conversions/DecimalToHexaDecimalTest.java | 14 ----- .../conversions/DecimalToHexadecimalTest.java | 14 +++++ 4 files changed, 56 insertions(+), 65 deletions(-) delete mode 100644 src/main/java/com/thealgorithms/conversions/DecimalToHexaDecimal.java create mode 100644 src/main/java/com/thealgorithms/conversions/DecimalToHexadecimal.java delete mode 100644 src/test/java/com/thealgorithms/conversions/DecimalToHexaDecimalTest.java create mode 100644 src/test/java/com/thealgorithms/conversions/DecimalToHexadecimalTest.java diff --git a/src/main/java/com/thealgorithms/conversions/DecimalToHexaDecimal.java b/src/main/java/com/thealgorithms/conversions/DecimalToHexaDecimal.java deleted file mode 100644 index 78838c61..00000000 --- a/src/main/java/com/thealgorithms/conversions/DecimalToHexaDecimal.java +++ /dev/null @@ -1,51 +0,0 @@ -package com.thealgorithms.conversions; - -// hex = [0 - 9] -> [A - F] -final class DecimalToHexaDecimal { - private DecimalToHexaDecimal() { - } - - 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', - '3', - '4', - '5', - '6', - '7', - '8', - '9', - 'A', - 'B', - 'C', - 'D', - 'E', - 'F', - }; - - // Returns the hex value of the dec entered in the parameter. - public static String decToHex(int dec) { - 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(); - } - - // Test above function. - public static void main(String[] args) { - System.out.println("Test..."); - int dec = 305445566; - String libraryDecToHex = Integer.toHexString(dec); - String decToHex = decToHex(dec); - System.out.println("Result from the library : " + libraryDecToHex); - System.out.println("Result decToHex method : " + decToHex); - } -} diff --git a/src/main/java/com/thealgorithms/conversions/DecimalToHexadecimal.java b/src/main/java/com/thealgorithms/conversions/DecimalToHexadecimal.java new file mode 100644 index 00000000..47a1e36b --- /dev/null +++ b/src/main/java/com/thealgorithms/conversions/DecimalToHexadecimal.java @@ -0,0 +1,42 @@ +package com.thealgorithms.conversions; + +/** + * This class provides a method to convert a decimal number to a hexadecimal string. + */ +final class DecimalToHexadecimal { + 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_MASK = 0x0F; + private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'}; + + private DecimalToHexadecimal() { + } + + /** + * Converts a decimal number to a hexadecimal string. + * @param decimal the decimal number to convert + * @return the hexadecimal representation of the decimal number + */ + public static String decToHex(int decimal) { + StringBuilder hexBuilder = new StringBuilder(SIZE_OF_INT_IN_HALF_BYTES); + for (int i = SIZE_OF_INT_IN_HALF_BYTES - 1; i >= 0; --i) { + int currentHalfByte = decimal & HALF_BYTE_MASK; + hexBuilder.insert(0, HEX_DIGITS[currentHalfByte]); + decimal >>= NUMBER_OF_BITS_IN_HALF_BYTE; + } + return removeLeadingZeros(hexBuilder.toString().toLowerCase()); + } + + private static String removeLeadingZeros(String str) { + if (str == null || str.isEmpty()) { + return str; + } + + int i = 0; + while (i < str.length() && str.charAt(i) == '0') { + i++; + } + + return i == str.length() ? "0" : str.substring(i); + } +} diff --git a/src/test/java/com/thealgorithms/conversions/DecimalToHexaDecimalTest.java b/src/test/java/com/thealgorithms/conversions/DecimalToHexaDecimalTest.java deleted file mode 100644 index 1105f457..00000000 --- a/src/test/java/com/thealgorithms/conversions/DecimalToHexaDecimalTest.java +++ /dev/null @@ -1,14 +0,0 @@ -package com.thealgorithms.conversions; - -import static org.junit.jupiter.api.Assertions.assertEquals; - -import org.junit.jupiter.api.Test; - -public class DecimalToHexaDecimalTest { - - @Test - public void testDecimalToHexaDecimal() { - assertEquals("000000be", DecimalToHexaDecimal.decToHex(190)); - assertEquals("00000708", DecimalToHexaDecimal.decToHex(1800)); - } -} diff --git a/src/test/java/com/thealgorithms/conversions/DecimalToHexadecimalTest.java b/src/test/java/com/thealgorithms/conversions/DecimalToHexadecimalTest.java new file mode 100644 index 00000000..c9817b5d --- /dev/null +++ b/src/test/java/com/thealgorithms/conversions/DecimalToHexadecimalTest.java @@ -0,0 +1,14 @@ +package com.thealgorithms.conversions; + +import static org.junit.jupiter.api.Assertions.assertEquals; + +import org.junit.jupiter.params.ParameterizedTest; +import org.junit.jupiter.params.provider.CsvSource; + +public class DecimalToHexadecimalTest { + @ParameterizedTest + @CsvSource({"0, 0", "1, 1", "10, a", "15, f", "16, 10", "255, ff", "190, be", "1800, 708"}) + void testDecToHex(int decimal, String expectedHex) { + assertEquals(expectedHex, DecimalToHexadecimal.decToHex(decimal)); + } +}