Question

What is the best way to approach translating this code into Java?
(the section called Convert Alpha-numeric Phone Number to All Numeric)
http://lawrence.ecorp.net/inet/samples/regexp-format.php

Since Java doesn’t have a lambda yet… what is the best approach for the String.replace ?

Answer 1

Wow, the original code is a bit over-verbose. I’d do:

return phoneStr.replace(/[a-zA-Z]/g, function(m) {
    var ix= m[0].toLowerCase().charCodeAt(0)-0x61; // ASCII 'a'
    return '22233344455566677778889999'.charAt(ix);
});

And consequently in Java, something like:

StringBuffer b= new StringBuffer();
Matcher m= Pattern.compile("[A-Za-z]").matcher(phoneStr);
while (m.find()) {
    int ix= (int) (m.group(0).toLowerCase().charAt(0)-'a');
    m.appendReplacement(b, "22233344455566677778889999".substring(ix, ix+1));
}
m.appendTail(b);
return b.toString();

Replacing with Java’s Matcher is clumsy enough that you might just prefer to use an array for this case:

char[] c= phoneStr.toLowerCase().toCharArray();
for (int i= 0; i<c.length; i++)
    if (c[i]>='a' && c[i]<='z')
        c[i]= "22233344455566677778889999".charAt((int) (c[i]-'a'));
return new String(c);