Deleting Files

Nepomuk

Hi!
I want to have my program delete some folders including all contents. For that, I wrote this method:
(Source being the filesname)

As you can see, it recursively walks through all directories and deletes all Files.

Now, I get the following output when I call it with delete("E:\\examples\\"):
As you can see, the file "E:\examples\TicTacToe\src\observerPattern\Observa ble.java" doesn't want to be deleted for some reason. If however I start the program (not the method - the program!) again, the output is:
It works fine. The File "Observable.java" isn't opened, I should have the rights to delete it and, as you see, it works when trying the second time. However, if I try to call the method twice after each other, the output is:
The output is the same, if I let it wait with
Does anyone have an idea, what the problem could be?

Greetings,
Nepomuk

Sep 13 '07 #1

dmjpro

Good Logic.
Try this code it will work.

Good Luck.

Kind regards,
Dmjpro.

Sep 13 '07 #2

JosAH

Good Logic.
Try this code it will work.

Expand|Select|Wrap|Line Numbers

1.       private static void delete(String source)
2.       {
3.           File tmp = new File(source);
4.           if(tmp.isDirectory() && tmp.list().length > 0)
5.           {
6.               System.out.print("** Directory: " + tmp.getName());
7.               String[] list = tmp.list();
8.               System.out.println(", List: " + Arrays.toString(list));
9.               for(int i=0;i<list.length;i++)
10.               {
11.                   //System.out.println("** Deleting " + source + File.separator + list);
12.                   delete(source + File.separator + list[i]);
13.               }
14.           }
15.           else{
16.                     if(tmp.delete())
17.                           System.out.println("** Deleted " + source);
18.                    else
19.                          System.out.println("** Not deleted " + source);
20.          }
21.       }
22.  

Good Luck.

Kind regards,
Dmjpro.

So if a File represents a directory which isn't empty it will not be deleted?
Fine logic ...

kind regards,

Jos

Sep 13 '07 #3

Nepomuk

Good Logic.
Try this code it will work.

Expand|Select|Wrap|Line Numbers

1.       private static void delete(String source)
2.       {
3.           File tmp = new File(source);
4.           if(tmp.isDirectory() && tmp.list().length > 0)
5.           {
6.               System.out.print("** Directory: " + tmp.getName());
7.               String[] list = tmp.list();
8.               System.out.println(", List: " + Arrays.toString(list));
9.               for(int i=0;i<list.length;i++)
10.               {
11.                   //System.out.println("** Deleting " + source + File.separator + list);
12.                   delete(source + File.separator + list[i]);
13.               }
14.           }
15.           else{
16.                     if(tmp.delete())
17.                           System.out.println("** Deleted " + source);
18.                    else
19.                          System.out.println("** Not deleted " + source);
20.          }
21.       }
22.  

Good Luck.

Kind regards,
Dmjpro.

Thanks for trying, but evidentially the result is the same. According to the printout, and as JosAH remarked, it now doesn't even try to delete some of files!

Any other ideas?

Greetings,
Nepomuk

Sep 13 '07 #4

madhoriya22

Thanks for trying, but evidentially the result is the same. According to the printout, and as JosAH remarked, it now doesn't even try to delete some of files!

Any other ideas?

Greetings,
Nepomuk

Hi,
What is the difference in ur code and dmjpro's code ?

Sep 13 '07 #5

Nepomuk

Hi,
What is the difference in ur code and dmjpro's code ?

It took me a while to figure that out - in line 15 he starts an else-block, which I don't have. That's all the difference.

Greetings,
Nepomuk

Sep 13 '07 #6

JosAH

It took me a while to figure that out - in line 15 he starts an else-block, which I don't have. That's all the difference.

Greetings,
Nepomuk

But an ever so important difference. Basically the flow runs as follows:

putting an 'else' before the last line completely changes the control flow.

@OP: I'm a bit surprised that your algorithm fails on some files/directories and
I don't have a solution for now, i.e. it sounds sensible as it is.

kind regards,

Jos

Sep 13 '07 #7

dmjpro

It took me a while to figure that out - in line 15 he starts an else-block, which I don't have. That's all the difference.

Greetings,
Nepomuk

Did you look at your O/P.
Your Code tries to delete Directory also.
That's why I put a else part.

Or there may be some Outputs.........!
Look at your Output.
The recursive call is not so easy as it seems.
The flow of control is very sensible.

Kind regards,
Dmjpro.

Sep 14 '07 #8

dmjpro

Did you look at your O/P.
Your Code tries to delete Directory also.
That's why I put a else part.

Expand|Select|Wrap|Line Numbers

1. Not deleted E:\examples\TicTacToe\src\observerPattern
2.  

Or there may be some Outputs.........!
Look at your Output.
The recursive call is not so easy as it seems.
The flow of control is very sensible.

Kind regards,
Dmjpro.

Sorry nepomuk!
Your logic is right.
No need to put a else part.
Your directory gets deleted when it is empty.
And this your code says............And it ll get called recursively by LIFO method of Stack.
So sorry! for misdirecting you.
I think your total problem starts with Observable.java.
Try it with another Directory tree, see what happens.
Is Observable.java can be deleted in a normal way after shutting down your System.

Kind regards,
Dmjpro.

Sep 14 '07 #9

Nepomuk

Sorry nepomuk!
Your logic is right.
No need to put a else part.
Your directory gets deleted when it is empty.
And this your code says............And it ll get called recursively by LIFO method of Stack.
So sorry! for misdirecting you.
I think your total problem starts with Observable.java.
Try it with another Directory tree, see what happens.
Is Observable.java can be deleted in a normal way after shutting down your System.

Kind regards,
Dmjpro.

No problem, everyone makes mistakes. ^^
I'm not so sure that the problem is with Observable.java - true, it's the file that cannot be deleted and therefore causes the others not to be deleted, but if I just start the whole program again when Observable.java and the directory it's in are the only files left, it works without a problem.

I'll check it with another directory right now and I'll post the result. Very weird stuff...

Greetings,
Nepomuk

Sep 14 '07 #10

Nepomuk

There, different directory, same problem. Here's the output of delete("E:\\junit4.4\\"):
(I left out a bit of info because of the CODE-Tag-Bug.)
And when starting it a second time without changing the file system:
Just to make sure, I tried it with another directory (E:\JavaBooks) and again:
But here, the second run gives me:
I checked, but I should be allowed to delete "galileocomputing_javainsel6.zip" - and I'm able to do so manually.

Just out of curiosity, I tried to delete that exact file with delete("E:\\JavaBooks\\Java ist auch eine Insel\\galileocomputing_javainsel6.zip") and the output was:
What could be wrong with those files? Why can't I delete them? I don't understand...

Greetings,
Nepomuk

Sep 14 '07 #11

JosAH

What could be wrong with those files? Why can't I delete them? I don't understand...

Greetings,
Nepomuk

Very strange indeed; the File class has a long history of bugs; would it help
if you invoke System.gc() just before you delete the file entry? I know it sounds
silly (and it is) but give it a try and let us know the results.

kind regards,

Jos

Sep 14 '07 #12

Nepomuk

Very strange indeed; the File class has a long history of bugs; would it help
if you invoke System.gc() just before you delete the file entry? I know it sounds
silly (and it is) but give it a try and let us know the results.

kind regards,

Jos

Thanks - it's strange, but with System.gc() I can make it work - but only if I wait as well. Here's the code I'm using:
and to call the method:
I have no idea, why I have to wait (and it won't work with 2,5 seconds, but with 3 seconds it will... any idea, why?), but at least it work's now. I guess, I'll check, if any files still exist and if so, wait and repeat... well, for a few times, not for ever.

Thanks for your help everybody!

Greetings,
Nepomuk

Sep 14 '07 #13