[Solved] count up to 16 with one digit

Newbie & Debugging Questions
#1

I’m working on a game where the player going to encounter a alien race, which is suppose to have a digit up to 16. I have manage to make the code that can translate Alien to Human. But not Human to Alien. I’m using A-G in the code for the 10-16 digits. How do I make the Human to Alien method?

Just in case someone wants/need to see my code that translate Alien to Human.


public static int fromAlienNumber(String nr){
        boolean isNegative = nr.contains("-");
        
        //Code to see if the number is compatible with the alien alphabet.
        Matcher m = Pattern.compile("(-?[0-9A-G]+)").matcher(nr);
        if(!m.matches()){
            System.err.println(nr+" is not an alien number");
            return -1;
        }
        
        int result = 0;
        nr = nr.replace("-","");
        
        for(int i=0; i<nr.length(); i++)           
            result += (int)(charToNumber(nr.charAt(i)) * Math.pow(10, nr.length()-(i+1)));              
        return isNegative ? -result : result;
    }
    
    public static int charToNumber(char c){
        switch(c){
            case '0': return 0;
            case '1': return 1;
            case '2': return 2;
            case '3': return 3;
            case '4': return 4;
            case '5': return 5;
            case '6': return 6;
            case '7': return 7;
            case '8': return 8;
            case '9': return 9;
            case 'A': return 10;
            case 'B': return 11;
            case 'C': return 12;
            case 'D': return 13;
            case 'E': return 14;
            case 'F': return 15;
            case 'G': return 16;

        }
        
        //To make the compiler happy, it should never come here.
        return -1;
    }