Close a file created with FileOutputStream, for a next delete

问题

I am currently facing some problem with a FileOutputStream in my Java code.

Actually I am using a FileOutputStream for creating a file, but then once the file is created there is no way for deleting it. As far as I could understand, this may come from the fact that the FileOutputstream is not closed.

On below my summarized code :

     outFile = new FileOutputStream(dir+"\\"+fileName);
     outFile.write("Test");
     outFile.flush();
     outFile.close();
     outFile = null;
     System.gc();

Then there is no way to delete the file, even "by hand". When my program is launched, I can't delete it on windows by a simple del. I also tried to remove content of the folder dir and it didn't worked neither, using this code :

static public void delDir( String place )

{
    File path = new File( place );
    System.out.println(path.exists());//return true
    if( path.exists() )
        {
        File[] f = path.listFiles();
        for( int j = 0 ; j < f.length ; j++ )
            {
            if( f[ j ].isDirectory() )
                {
                deleteDirectory( path+"\\"+f[ j ] );
                }
            f[ j ].delete();
            }
        }
}

So my question is : How to close this file for a next delete (or how to delete it properly if we can't close it)?

回答1:

It is a bug in Java. Yes it it rarely but they exists ;) Could you add after outFile.close()

outFile = null;
System.gc();

And then try to delete it. There are more possiblity if this is not working. Let me know.

UPDATE

For me it works:

public class FileDeleteExample {
    public static void main(String[] args) throws Exception {
        File f = new File("test.txt");

        FileOutputStream outFile = null;

        try {
            outFile = new FileOutputStream(f);
            outFile.write("Test".getBytes());
        } finally {
            outFile.flush();
            outFile.close();
            outFile = null;
            System.gc();
        }

        f.delete();
    }
}

UPDATE

I tried it with the example Sumit Singh mentioned by deleting the lines outFile=null; System.gc; and this works as well for me. So there should'nt be a problem with the FileOutputStream. Could you try the little example above and say whether it works or not?

UPDATE

void closeQuietly(FileOutputStream out) {
    try { out.flush(); out.close(); } catch(Exception e) {} 
}

Now just call the method in the finally block!

回答2:

I had the same problem, the delete() method returned false for my File.

In my case, somewhere in between creating the file, writing to its FileOutputStream and deleting the file, i was using a FileInputStream and forgot to call close() for it.

So, maybe somewhere in your code you attached another stream to this file, and left it open.

Before finding the real source of the problem, i used a simle hack to temporarily fix this:

FileOutputStream fos = new FileOutputStream(myFile);
fos.close();
myFile.delete();

Right before calling delete on my File, i created another FileOutputStream over it and then just called close().

This unlocks all previuous locks on this file and lets you call delete().

Still it is not a good practice to do this. You should find out who uses your file and solve it the right way.

回答3:

Well, the way to close a file output and input streams is:

name.close()

and your deletion code looks fine. My recommendation would be to use FileIO instead of FileOutputStream, unless you're using FileOutputStream for a good reason. Can you delete the file once the program closes?

回答4:

You can try this code..

    File file = new File(dir+"\\"+fileName);
    FileOutputStream outFile;
    try {
        outFile = new FileOutputStream(file);
        outFile.write("Test".getBytes());
        outFile.flush();
        outFile.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
   file.delete();

You can check these below links..

I can't delete a file in java
Java 'file.delete()' Is not Deleting Specified File!
Java 6 File Deletion

回答5:

Better to use FileUtils.deleteDirectory from Apache Commons IO. Overcomes the Java delete bug, reduces amount of code used and most of all, it works.

Instead of calling

delDir(place);

just call

FileUtils.deleteDirectory(new File(place));

Update: In your delDir method, you call:

deleteDirectory(new File(path + "\\" + f[j]));

but the result of

File[] f = path.listFiles();

will already include the path in the file, so you can just use:

deleteDirectory( f[j].getPath() );

回答6:

Not really related but:

This solution of the closing of a file helped me with another problem. When run a programme from java 6 the new process was suspended until I closed my application (in java 7 it was ok). The solution based on this answer helped:

    String[] com = new String[]{javaRun, arg1, arg2, arg3, arg4};

    Process proc = Runtime.getRuntime().exec(com, null, dir);

    proc = null;
    System.gc();

This works with java 6. Thanks for inspiration.

回答7:

The problem may be in the first line: outFile = new FileOutputStream(dir+"\"+fileName);

Not sure the new is required.
Don't believe the directory should be included in the path. AFAIK the directory for FileOutputStream is defined as the app internal directory.

HTH

来源：https://stackoverflow.com/questions/12096002/close-a-file-created-with-fileoutputstream-for-a-next-delete

标签

java

delete-file

fileoutputstream