package test; import java.util.HashMap; /** * * @author Matt Torvalds */ public class HexToBinary { private static final HashMap map = new HashMap(); static { map.put('0', "0000"); map.put('1', "0001"); map.put('2', "0010"); map.put('3', "0011"); map.put('4', "0100"); map.put('5', "0101"); map.put('6', "0110"); map.put('7', "0111"); map.put('8', "1000"); map.put('9', "1001"); map.put('A', "1010"); map.put('B', "1011"); map.put('C', "1100"); map.put('D', "1101"); map.put('E', "1110"); map.put('F', "1111"); } public static void main(String[] args) { final char[] hex = args[0].toCharArray(); final StringBuilder sb = new StringBuilder(); for (int i = 0; i < hex.length; i++) { sb.append(map.get(hex[i])); } System.out.println(sb.toString()); } }