Question

So I’m working with a huge dataset in Java trying to scrub the text of everything but alpha characters. Right now I’m doing this with:

snippet = snippet.toLowerCase();
snippet.replaceAll("[^A-Za-z]", "");                

however the sanitization is not going as planned. Some extraneous @, #, ?, and : are making their way through. Ideas?

Answer 1

In java, Strings are immutable – their value can’t be changed. Consequently, replaceAll() returns the altered String; it doesn’t change the String on which it was called.

You must assign the return value back to the variable:

snippet = snippet.replaceAll("[^A-Za-z]", "");

Although this behaviour at first seems “non Object Oriented”, when the class is immutable it does make sense.

Also, you don’t need the call to .toLowerCase() – you regex is matching on uppercase letters too.