Stripping Strings of all non alphanumeric characters and spaces

Question

I've been searching the forums and digging through the String class, but can't seem to find an answer.
What I need to do is turn any string, such as "Sir, please pass the fish."
into: "sirpleasepassthefish". The easy part is using allLowerCase which gets it down to "sir, please pass the fish.", but now I need to able to remove all space, commas, exclamation points or whatever other junk that could be in a sentence. Is there any thing in the String fucntion that does it that I missed, or do I have to make my own class to do it?
Thanks!

Answer 1

Ok, the last part of the code isn't working:
sentence = "Dad, bob";
sentence = sentence.toLowerCase();
int length = sentence.length();
char test;
int a =10; //for TESTING
ArrayList pal = new ArrayList(length);
for (int x = 0; x<length; x++)
test = sentence.charAt(x);
g.drawString("" + test, 30, a); //for TESTING
a +=20; //for TESTING
if ((test > 'a') && (test < 'z'))
pal.add(sentence.substring(x, x+1));
the IF statement is allowing everything through, and not stripping any spaces or the comma or such, what am I missing?