Member Avatar for skiplatte

I'm getting StringIndexOutOfBoundsException when I try to reasign the value of a variable. protString = protString.substring(newRPos+1, input.length()); I understand that this is something I would rather not do... but as I don't know the index of newRPos I can't think of another way to iterate.

Thanks

Edited by peter_budo because: Correcting code tags
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Mixing lengths from two different strings is the most likely cause. If you call substring on protString but pass input.length() as the end index, that end index can exceed protString.length() and trigger the exception. pointed you toward a bounds check and rightly pointed at the String API; the practical follow-ups are to verify which string you mean to slice and to confirm the numeric bounds before calling substring.

Practical steps to diagnose and fix:

  • Log or inspect newRPos, protString.length() and input.length() at the moment just before the substring call.
  • Guard against newRPos == -1 (if it came from indexOf) and against negative values.
  • If you want the remainder of protString after newRPos, prefer the one-argument substring(beginIndex) or keep an explicit cursor instead of repeatedly reassigning the original string. Example pattern:
int cursor = newRPos + 1;
if (newRPos != -1 && cursor <= protString.length()) {
    String tail = protString.substring(cursor); // returns "" if cursor == length
    // process tail or advance cursor without mutating protString
}

If you perform many such slices in a loop, avoid repeated immutable-string allocations by tracking a cursor or using StringBuilder for in-place edits. See the Java String documentation and the StringBuilder class for exact behavior and performance notes: String (Java SE 8) javadoc and StringBuilder (Java SE 8) javadoc.

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Member Avatar for masijade

Then also check with if (newRPos < protString.length) . Also, is there any guarantee that input.length() is going to be larger than newRPos, as both of those are indexes (i.e. a start index and an end index) not a start and length, and I don't know how substring reacts if the end index is smaller than the start index..

Member Avatar for JamesCherrill

... I don't know how substring reacts if the end index is smaller than the start index..

API doc states:

Throws: IndexOutOfBoundsException - if the beginIndex is negative, or endIndex is larger than the length of this String object, or beginIndex is larger than endIndex.

Member Avatar for masijade

API doc states:

Thanks. That was just me being too lazy to look it up myself, and hoping the OP would figure out to do that. ;-)

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