java分裂混淆空间字符

Question

I am splitting a string which contains a filename from a windows system. The string uses the ascii FS to separate the filename from other information

eg filename.jpgFSotherInformationFSanotherPartOfInformation

Here some example code:

String fs = new String(new byte[]{(byte)32}); 
String information ="filename (copy).jpg"+fs+"otherInformation"; 
String[] parts = information.split(fs);

Why does split confuse the space-separator with the ascii-FS?

Should I use a different function that split? Pattern.quote(fs) does help either... :-(

Answer 1

Because FS is not ascii value 32.

http://bestofthisweb.com/blogs/tag/ascii-table/

The FS is character 28, but this control character should not be used in file names, only for some rare binary file formats (I don't know of one which uses it anymore)

The space character is 32 which is why it looks the same the split, because it is.

For a simple field seperator, I suggest you use ',' or '\\t' which can be easily read as text or using a spreadsheet package.

I would suggest stepping through the code in a debugger so you can see what you program is doing.

Answer 2

You've initialized fs with a space (in a rather complicated way). The following is equal and shows your problem:

String fs = " "; 
String information ="filename (copy).jpg"+fs+"otherInformation"; 
String[] parts = information.split(fs);

The ascii char FS has the number 0x1C , so this should work properly:

String fs = "\u001C"; 
String information ="filename (copy).jpg"+fs+"otherInformation"; 
String[] parts = information.split(fs);

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Background information

The file separator FS is an interesting control code, as it gives us insight in the way that computer technology was organized in the sixties. We are now used to random access media like RAM and magnetic disks, but when the ASCII standard was defined, most data was serial. I am not only talking about serial communications, but also about serial storage like punch cards, paper tape and magnetic tapes. In such a situation it is clearly efficient to have a single control code to signal the separation of two files. The FS was defined for this purpose. (source)

The FS was invented to separate real files and not filenames in a hierarchical file directory. Technically, yes, you can use it, but it has a different meaning.

Answer 3

Beacuse FS is Ascii values 28

Ascii value 32 is space

Answer 4

Split's parameter is actually a regular expression, have you tried

String[] parts = information.split("\\x20");

Or even

String[] parts = information.split("\\s");