Java Data Type How to - Convert A Number To Hexadecimal

Question

We would like to know how to convert A Number To Hexadecimal.
Answer

public class Main {
  public static String ConvertToHexadecimal(int num) {
    int r;/* w w w. j av  a2s . c  om*/
    String bin = "\0";
    do {
      r = num % 16;
      num = num / 16;

      if (r == 10)
        bin = "A" + bin;

      else if (r == 11)
        bin = "B" + bin;

      else if (r == 12)
        bin = "C" + bin;

      else if (r == 13)
        bin = "D" + bin;

      else if (r == 14)
        bin = "E" + bin;

      else if (r == 15)
        bin = "F" + bin;

      else
        bin = r + bin;
    } while (num != 0);

    return bin;
  }

  public static int ConvertFromHexadecimalToDecimal(String num) {
    int a;
    int ctr = 0;
    double prod = 0;

    for (int i = num.length(); i > 0; i--) {

      if (num.charAt(i - 1) == 'a' || num.charAt(i - 1) == 'A')
        a = 10;

      else if (num.charAt(i - 1) == 'b' || num.charAt(i - 1) == 'B')
        a = 11;

      else if (num.charAt(i - 1) == 'c' || num.charAt(i - 1) == 'C')
        a = 12;

      else if (num.charAt(i - 1) == 'd' || num.charAt(i - 1) == 'D')
        a = 13;

      else if (num.charAt(i - 1) == 'e' || num.charAt(i - 1) == 'E')
        a = 14;

      else if (num.charAt(i - 1) == 'f' || num.charAt(i - 1) == 'F')
        a = 15;

      else
        a = Character.getNumericValue(num.charAt(i - 1));
      prod = prod + (a * Math.pow(16, ctr));
      ctr++;
    }
    return (int) prod;
  }

  public static void main(String[] args) {
    int num;
    String numS;
    num = 123;
    System.out.println(ConvertToHexadecimal(num));
    numS = "123";
    System.out.println(ConvertFromHexadecimalToDecimal(numS));
  }
}