Question about the String.replaceAll() and String.replaceFirst() method.

Question

I need to do a simple string replace operation on a segment of string. I ran into the following issue and hope to get some advice.

1. In the original string I got, I can replace the string such as <div class="more"> to something else.
2. BUT, in the same original string, if I want to replace a much long string such as the following, it won’t work. Nothing gets replaced after the call.

<div class="more"><a href="http://SERVER_name/profiles/atom/mv/theboard/entries/related.do?email=xyz.com&amp;amp;ps=20&amp;amp;since=1273518953218&amp;amp;sinceEntryId=abc-def-123-456"&gt;More...&lt;/a&gt;&lt;/div&gt;

I tried these two methods:

originalString.replaceFirst(moreTag, newContent);
originalString.replaceAll(moreTag, newContent);

Thanks in advance.

Answer 1

You need to get hold of the result of the replacement and use it further:

String newString = originalString.replaceFirst(moreTag, newContent);
System.out.println(newString);

Explanation: strings in Java are immutable. The behavioral methods of java.lang.String won't change the internal value. They instead will return the modified result.

If that still doesn't return the desired result, then the moreTag simply didn't match anything. The methods you mentioned expects a regular expression. You can find in the Pattern javadoc how to compose a valid regex pattern.

Answer 2

Can you show us your code ?

Are you aware that your moreTag string (the first argument to replaceFirst/replaceAll) is assumed to be a regular expression ?

If you dont want regular expressions here, you can use the plain replace method.

Answer 3

Strings are immutable, do you save the result of replace operation?

Test you regular expression if it really matches what do you think, you'll find some tools for that online. Especially take care of proper escaping of special characters.

Also, if you do not need regular expressions, consider using StringTokenizer and StringBuilder.