Question

I have this regex to test for telephone # that should be a toll free.

public static final Pattern patternTollFree = Pattern.compile("^((877)|(800)|(866)|(888))");

So I only want to get those # where the user may have left the 1 off of the front of the string, but I have tried several things and I can’t get java to match.

public String changeRingTo( String changedRinger )
{
    if ( null == changedRinger || changedRinger.length() != 10)
        return changedRinger;
    if ( patternTollFree.matcher(changedRinger).region(0, 2).matches() )
        changedRinger = '1' + changedRinger;
    return changedRinger;
}

I can’t get this 2nd test case below to succeed. What am I doing wrong?

assertEquals( "Regex not working", "8189091000", of.changeRingTo("8189091000"));
assertEquals( "Regex not working", "18769091000", of.changeRingTo("8769091000"));

Answer 1

Your second test case fails because it starts with 876 which is not a valid toll free prefix. Additionally, as indicated in the other answer, you should change region(0, 2) to region(0, 3) although that entire line could be significantly simplified.