ToDecimal exercise

ToDecimal.java

public class ToDecimal {

    public static void main(String[] args) {
        if (args.length == 0) {
            System.out.println("illegal input");
            return;
        }

        String decimalInBinary = args[0];
        if (!decimalInBinary.matches("^(0|1)+$")) {
            System.out.println("illegal input");
            return;
        }

        int number = 0;
        for (int i = 0, power=decimalInBinary.length()-1; i < decimalInBinary.length() ; i++, power--) {
            number += Character.getNumericValue(decimalInBinary.charAt(i)) * Math.pow(2, power);
        }
        System.out.println(number);
    }
}