Java String contains extraneous data -

-

i have input in utf16le encoding. time input reaches code been through fileinputstream encased in filereader encased in linenumberreader.

the first line read gives string like:

"1 piece of data string"

however, looking string value along lines of:

[, 1, p, i, ...]

notice empty element start.

no string passed through couple of functions here , there, converted object , being put through paces. @ point, should first part of string (the 1 or in case number including decimals) passed function has parse actual number.

the content of string appears "1" in value says: 

[, 1, p, i, ...]

so whole string still in there.

in case returns parseexception , print unparseable number exception messages , logging tels me "1" unparseable number.

the real problem appears leading empty element subsequent lines show similar behavior except leading empty element , parse.

a string (at least implementation in openjdk) stores char[], offset , count. actual content of string characters in char[] indices offset offset+count.

that means char[] can hold more characters string represents.

this done in order able share char[]s between different string instances.

for example, if have string value foobar , call .substring(3) on it, resulting string represent bar, may reference same char[]. second string have offset 3 bigger originals string , count that's 3 smaller.

all of works because string objects immutable: since no single string ever modify it's char[] in way, it's safe them share it.

this means inspecting string object in debugger might give false impression. therefore safest thing if want inspect string character-for-character call either tochararray() or call charat() in loop.


Comments

Post a Comment

Popular posts from this blog

javascript - Enclosure Memory Copies -

-
function myclass() { //lots , lots of vars , code here. this.bar = function() { //do numerous enclosed myclass vars } this.foo = function() { alert('hello'); //don't enclosed variables. } } each instance of myclass gets own copy of bar , foo, why prototyped methods use less memory. however, know more memory use of inner methods. it seems obvious me (1) below must true. agree? not distinct myclass instances have own distinct copies of bar, must have own distinct copies of myclass enclosure. (or else how bar method keep myclass variables straight on per instance basis?) now (2) question i'm after. since inner foo method doesn't use in myclass enclosure natural qustion is: javascript smart enough not keep myclass enclosure in memory use of foo? this depend entirely on implementation not language. naive implementations keep far more around others. answer true e.g. v8 (chrome's js engine) may not true spider...
Read more

php - Replacing tags in braces, even nested tags, with regex -

-
example preg_replace('/\{[a-za-z.,\(\)0-9]+\}/', 'replaced', 'lorem ipsum dolor sit {tag1({tag2()})}, consectetur adipiscing elit.'); the result: lorem ipsum dolor sit {tag1(replaced)}, consectetur adipiscing elit. question as can see "tag2" has been replaced, want replace "tag1" know how can this? (in cases might this: {tag1({tag2({tag3()})})}) , on.) btw using preg_replace_callback, easier show preg_replace here site can test code: http://www.spaweditor.com/scripts/regex/index.php you need add curly braces character set. here's pattern used: /\{[a-za-z.,\(\)\{\}0-9]+\}/ and here result: "lorem ipsum dolor sit replaced, consectetur adipiscing elit."
Read more