Java searching for a substring URL in a string URL

I have a couple of URLs:

a. https://iamterribleatthis/a

b. https://iamterribleatthis/a/index.html

I'm using Apache stringutls to see if 'a' is present in 'b' but I think that the forward slash is failing the comparison. Is there an easier/better way to find if 'a' is present in 'b' including the forward slash? Thanks.