Problem with code: reading a string

Question

Hi,
I am very new to java so excuse my naivety. i need to write some code which will decode an encrypted message. the message is stored as a string which is a series of integers which. Eg. Nick in this code is 1409030110 where a = 1, b = 2,... and there is a 0 (zero) after every word. at the moment the code only goes as far as seperating the individual characters in the message up and printing them out onscreen.
Heres the code:
int index = 0;
while(index < line.length() - 1) {
char first = line.charAt(index);
char second = line.charAt(index + 1);
if(second == 0) {
char third = line.charAt(index + 2);
if(third == 0) {
System.out.print(first + "" + second);
index = index + 3;
else {
System.out.print(first);
index = index + 2;
else {
System.out.print(first + "" + second);
index = index + 3;
Basically its meant to undo the code by reading the first two characters in the string then determining whether the second is equal to 0 (zero). if the second is 0 then it needs to decide whether the third character is 0 (zero) because the code could be displaying 10 or 20. if so the first two characters are recorded to another string and if not only the first is recorded. obviously if the second character is not a zero then the code will automatically record the first 2 characters.
my problem is that the code doesnt seem to recognise the 0 (zero) values. when i run it thru with the string being the coded version of Nick above (1409030110) the outputted answer is 1490010 when it should be 149311. as far as i can see the code is right but its not working! basically the zeros are begin removed but i need each group of non-zero digits to be removed seperately so i can decode them.
if anyone has understood any of this could you give me some advice, im at my wits end!
Thanks, Nick

Answer 1

Try something like this:
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.util.Properties;
public class SimpleDecoder
    /** Default mapping file */
    public static final String DEFAULT_MAPPING_FILE = "SimpleDecoder.properties";
    /** Regular expression pattern to match one or more zeroes */
    public static final String SEPARATOR = "0+";
    private Properties decodeMapping = new Properties();
    public static void main(String [] args)
        try
            SimpleDecoder decoder = new SimpleDecoder();
            decoder.setDecodeMapping(new FileInputStream(DEFAULT_MAPPING_FILE));
            for (int i = 0; i < args.length; ++i)
                System.out.println("Original encoded string: " + args);
System.out.println("Decoded string : " + decoder.decode(args[i]));
catch (Exception e)
e.printStackTrace();
public void setDecodeMapping(InputStream stream) throws IOException
this.decodeMapping.load(stream);
public String decode(final String encodedString)
StringBuffer value = new StringBuffer();
String [] tokens = encodedString.split(SEPARATOR);
for (int i = 0; i < tokens.length; ++i)
value.append(this.decodeMapping.getProperty(tokens[i]));
return value.toString();
I gave your "1409030110" string on the command line and got back "nick". The SimpleDecoder.properties file had 26 lines in it:
1 = a
2 = b
3 = c
// etc;Not a very tricky encryption scheme, but it's what you asked for. - MOD