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PODetermine if a String is a number and convert in Java?
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  1. PODetermine if a String is a number and convert in Java?
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    copied!<p>I know variants of this question have been asked frequently before (see <a href="https://stackoverflow.com/questions/1163615/java-library-to-check-whether-a-string-contains-a-number-without-exceptions">here</a> and <a href="https://stackoverflow.com/questions/1097332/convert-a-string-to-number-java">here</a> for instance), but this is <strong>not</strong> an <strong>exact</strong> duplicate of those.</p> <p>I would like to check if a <code>String</code> is a number, and if so I would like to store it as a <code>double</code>. There are several ways to do this, but all of them seem inappropriate for my purposes.</p> <p>One solution would be to use <code>Double.parseDouble(s)</code> or similarly <code>new BigDecimal(s)</code>. However, those solutions don't work if there are commas present (so "1,234" would cause an exception). I could of course strip out all commas before using these techniques, but that would seem to pose loads of problems in other locales.</p> <p>I looked at Apache Commons <code>NumberUtils.isNumber(s)</code>, but that suffers from the same comma issue.</p> <p>I considered <code>NumberFormat</code> or <code>DecimalFormat</code>, but those seemed far too lenient. For instance, "1A" is formatted to "1" instead of indicating that it's not a number. Furthermore, something like "127.0.0.1" will be counted as the number 127 instead of indicating that it's not a number.</p> <p>I feel like my requirements aren't so exotic that I'm the first to do this, but none of the solutions does exactly what I need. I suppose even I don't know <strong>exactly</strong> what I need (otherwise I could write my own parser), but I know the above solutions do not work for the reasons indicated. Does any solution exist, or do I need to figure out precisely what I need and write my own code for it?</p>
 

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