JavaAlgorithms/Conversions/HexaDecimalToBinary.java

package Conversions;

// Hex [0-9],[A-F] -> Binary [0,1]

public class HexaDecimalToBinary {

  private final int LONG_BITS = 8;

  public void convert(String numHex) {
    // String a HexaDecimal:
    int conHex = Integer.parseInt(numHex, 16);
    // Hex a Binary:
    String binary = Integer.toBinaryString(conHex);
    // Output:
    System.out.println(numHex + " = " + completeDigits(binary));
  }

  public String completeDigits(String binNum) {
    for (int i = binNum.length(); i < LONG_BITS; i++) {
      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) {
      objConvert.convert(num);
    }
  }
}