Why doesn't java.io.File have a close method?
While java.io.RandomAccessFile
does have a close()
method java.io.File
doesn't. Why is that? Is the file closed automatically on finalization or so开发者_如何学编程mething?
The javadoc of the File
class describes the class as:
An abstract representation of file and directory pathnames.
File
is only a representation of a pathname, with a few methods concerning the filesystem (like exists()
) and directory handling but actual streaming input and output is done elsewhere. Streams can be opened and closed, files cannot.
(My personal opinion is that it's rather unfortunate that Sun then went on to create RandomAccessFile
, causing much confusion with its inconsistent naming.)
java.io.File
doesn't represent an open file, it represents a path in the filesystem. Therefore having close
method on it doesn't make sense.
Actually, this class was misnamed by the library authors, it should be called something like Path
.
Essentially random access file wraps input and output streams in order to manage the random access. You don't open and close a file, you open and close streams to a file.
A BufferedReader can be opened and closed but a File is never opened, it just represents a path in the filesystem.
Say suppose, you have
File f = new File("SomeFile");
f.length();
You need not close the File
s, because its just the representation of a path.
You should always consider to close only reader/writers and in fact streams.
As already stated, the File class does not have a closing method as it's merely a path or a reference to the actual File.
You will usually use this File class as a helper to open the actual file with a FileReader class which you can close. That said, it does close itself on exit but if you read a file from your program and then try to do something to this file externally, it could result in an error on that external call, so it's better to close it
File path = new File(/some/path/file.txt);
FileReader actualFile = new FileReader(path);
...<
if(imDoneWithTheFile)
actualFile.close();
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