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 something?
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3If you look into Java API, you will be able to get the answer immediately.gigadot– gigadot2011-01-20 20:37:32 +00:00Commented Jan 20, 2011 at 20:37
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55I've learned that people are more helpful than the otherwise superb Java spec.Albus Dumbledore– Albus Dumbledore2011-01-20 20:40:40 +00:00Commented Jan 20, 2011 at 20:40
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7b/c it cannot be opened :)bestsss– bestsss2011-01-20 20:45:43 +00:00Commented Jan 20, 2011 at 20:45
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6Because it doesn't open anything. And people are considerably less reliable than the offical Java specification.user207421– user2074212014-12-18 10:08:43 +00:00Commented Dec 18, 2014 at 10:08
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6 Answers
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.)
Comments
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.
3 Comments
biziclop
But then what about all the directory listing methods? They should've been separated from the
Path completely.
maaartinus
Agreed, but in any case, either File or RandomAccessFile is wrongly named. Something like RandomAccessFileStream could be better, but it's many year too late now.
mins
"Actually, this class was misnamed by the library authors, it should be called something like Path" --> They heard you. In the nio (New I/O) package, the similar classe is now named Path. docs.oracle.com/javase/7/docs/api/java/nio/file/Path.html
A BufferedReader can be opened and closed but a File is never opened, it just represents a path in the filesystem.
Comments
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.
1 Comment
Steve Cohen
Yes. I never looked much into java.io.RandomAccessFile. I always assumed it overrode java.io.File but it does not!. File represents a path. RandomAccessFile is an object that can perform disk I/O as streams can, albeit with a much different implementation, to allow random rather than streamed access.
Say suppose, you have
File f = new File("SomeFile");
f.length();
You need not close the Files, because its just the representation of a path.
You should always consider to close only reader/writers and in fact streams.
answered May 20, 2013 at 19:25
Balaji Boggaram Ramanarayan
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Comments
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();
1 Comment
MrThaler
This will fail to close your FileReader if there is an exception somewhere in your hidden block of code. You should always use try-with-resources to close an object implementing the Closeable/AutoCloseable interface, or if you are for some reason unable to (a very old Java version perhaps) do so in a finally-block.