Hexadecimal to dual

gistfile1.java

String hexString = "12345";
StringBuffer binaryString = new StringBuffer();
Integer n = 0,
        dualInt = 0,
        currentNumber = 0;
// hex2dual
for ( int i = hexString.length() - 1; i >= 0; i-- ) {
    int a,
        b = (new Double(Math.pow(16, n))).intValue();
    char character = hexString.charAt(i);
    if (character == 'A') {
        a = 10;
    } else if (character == 'B') {
        a = 11;
    } else if (character == 'C') {
        a = 12;
    } else if (character == 'D') {
        a = 13;
    } else if (character == 'E') {
        a = 14;
    } else if (character == 'F') {
        a = 15;
    } else {
        a = Integer.parseInt((new Character(character)).toString());
    }
    int value = a * b;
    dualInt = dualInt + value;
    n++;
    // System.out.println(a + " * " + b + " = " + value);
}
// dual2binary
currentNumber = dualInt;
while (currentNumber > 0) {
    Integer remain = currentNumber / 2;
    Integer modulo = currentNumber % 2;
    binaryString.insert(0, modulo.toString());
    // System.out.println(currentNumber + " : 2 = " + remain + " Rest: " + modulo);
    currentNumber = remain;
}
System.out.println(binaryString.toString());