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POHow do I avoid the implicit "^" and "$" in Java regular expression matching?
 

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  1. POHow do I avoid the implicit "^" and "$" in Java regular expression matching?
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    <p>I've been struggling with doing some relatively straightforward regular expression matching in Java 1.4.2. I'm much more comfortable with the Perl way of doing things. Here's what's going on:</p> <p>I am attempting to match /^&lt;foo&gt;/ from "&lt;foo&gt;&lt;bar&gt;"</p> <p>I try:</p> <pre><code>Pattern myPattern= Pattern.compile("^&lt;foo&gt;"); Matcher myMatcher= myPattern.matcher("&lt;foo&gt;&lt;bar&gt;"); System.out.println(myMatcher.matches()); </code></pre> <p>And I get "false"</p> <p>I am used to saying:</p> <pre><code>print "&lt;foo&gt;&lt;bar&gt;" =~ /^&lt;foo&gt;/; </code></pre> <p>which does indeed return true.</p> <p>After much searching and experimentation, I discovered <a href="http://book.javanb.com/java-regular-expressions-taming-the-java-util-regex-engine/LiB0055.html" rel="nofollow noreferrer"> this</a> which said:</p> <p>"The String method further optimizes its search criteria by placing an invisible ^ before the pattern and a $ after it."</p> <p>When I tried:</p> <pre><code>Pattern myPattern= Pattern.compile("^&lt;foo&gt;.*"); Matcher myMatcher= myPattern.matcher("&lt;foo&gt;&lt;bar&gt;"); System.out.println(myMatcher.matches()); </code></pre> <p>then it returns the expected true. I do not want that pattern though. The terminating .* should not be necessary.</p> <p>Then I discovered the Matcher.useAnchoringBounds(boolean) method. I thought that expressly telling it to not use the anchoring bounds would work. It did not. I tried issuing a</p> <pre><code>myMatcher.reset(); </code></pre> <p>in case I needed to flush it after turning the attribute off. No luck. Subsequently calling .matches() still returns false.</p> <p>What have I overlooked?</p> <p>Edit: Well, that was easy, thanks.</p>
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    1. COFYI, useAnchoringBounds() and useTransparentBounds() only come into play when you've used the region() method to limit matches to a subset of the original target text. If you haven't done that, those methods have no effect.
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      1. USAlan Moore
 

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