JavaAlgorithms/Conversions/DecimalToHexaDecimal.java

package Conversions;

// 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 = {
    '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(sizeOfIntInHalfBytes);
    hexBuilder.setLength(sizeOfIntInHalfBytes);
    for (int i = sizeOfIntInHalfBytes - 1; i >= 0; --i) {
      int j = dec & halfByte;
      hexBuilder.setCharAt(i, hexDigits[j]);
      dec >>= numberOfBitsInAHalfByte;
    }
    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);
  }
}