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    <p>I seem to recall that the strings in Java were stored as the actual characters along with a start and length.</p> <p>This means that a substring string can share the same characters (since they're immutable) and only have to maintain a separate start and length.</p> <p>So I'm not entirely certain what your memory issues are with the Java strings.</p> <hr> <p>Regarding that article posted in your edit, it seems a bit of a non-issue to me.</p> <p>Unless you're in the habit of making huge strings, then taking a small substring of them and leaving those lying around, this will have near-zero impact on memory.</p> <p>Even if you had a 10M string and you made 400 substrings, you're only using that 10M for the underlying char array - it's not making 400 copies of that substring. The only memory impact is the start/length bit of each substring object.</p> <p>The author seems to be complaining that they read a huge string into memory then only wanted a bit of it, but the entire thing was kept - my suggestion would be they they might want to rethink how they process their data :-)</p> <p>To call this a Java bug is a huge stretch as well. A bug is something that doesn't work to specification. This was a <em>deliberate</em> design decision to improve performance, running out of memory because you don't understand how things work is not a bug, IMNSHO. And it's definitely <em>not</em> a memory leak.</p> <hr> <p>There was one <em>possible</em> good suggestion in the comments to that article, that the GC could more aggressively recover bits of unused strings by compressing them.</p> <p>This is <em>not</em> something you'd want to do on a first pass GC since it would be relatively expensive. However, where every other GC operation had failed to reclaim enough space, you could do it.</p> <p>Unfortunately it would almost certainly mean that the underlying <code>char</code> array would need to keep a record of all the string objects that referenced it, so it could both figure out what bits were unused <em>and</em> modify all the string object start and length fields.</p> <p>This in itself may introduce unacceptable performance impacts and, on top of that, if your memory is so short for this to be a problem, you may not even be able to allocate enough space for a smaller version of the string.</p> <p>I think, if the memory's running out, I'd probably prefer <em>not</em> to be maintaining this char-array-to-string mapping to make this level of GC possible, instead I would prefer that memory to be used for my strings.</p> <hr> <p>Since there is a perfectly acceptable workaround, and good coders should know about the foibles of their language of choice, I suspect the author is right - it <em>won't</em> be fixed.</p> <p>Not because the Java developers are too lazy, but because it's not a problem.</p> <p>You're free to implement your <em>own</em> string methods which match the C# ones (which don't share the underlying data except in certain limited scenarios). This will fix your memory problems but at the cost of a performance hit, since you have to copy the data every time you call substring. As with most things in IT (and life), it's a trade-off.</p>
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    1. PODanger of C# Substring method?
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    1. COhttp://nflath.com/2009/07/the-dangers-of-stringsubstring/
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    2. COI have to disagree with the statement *"running out of memory because you don't know how things work is not a bug"*. The documentation for substring states: `Returns a new string that is a substring of this string`. It gives no hint that that the returned string is *pinning the original string in memory*. So the docs should either clearly state the *actual behavior* or this "optimization" should be eschewed. It's your pick - either the docs is flawed or the implementation is. Developers shouldn't have to examine the internal implementation of such methods understand how to use them correctly.
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