Before you get excited I have not solved the problem but my experiments might give someone else a clue.

I created this sketch which

1. reads a file of uppercase letters
2. converts the data to lowercase
3. writes the lowercase letters to a temporary file
4. deletes the original file
5. renames the temp file as the orignal file

The first 3 steps work just fine and although the two files exist the last two steps fail here is the ouput. The last 2 lines report that the deletion and renaming of the files failed.

C:\Users\Peter\Documents\Processing\Forum01\FileTest\data\kick.txt  true
C:\Users\Peter\Documents\Processing\Forum01\FileTest\data\temp.txt  true
false
false

I decided to try this in Eclipse and I ran the code in debug mode it failed in the same way BUT if I ran the code it worked perfectly and the delete and rename reported success.

BTW dataPath("") appends the dat folder so line 20 would be

String fileName = dataPath("/kick.wav");

1. import java.io.*;
2. byte[] kickFile ;  // to store a loaded wav file
3. 
   
4. void setup() {
5.   // load a text file of uppercase letters
6.   kickFile = loadBytes("/data/kick.txt");
7. println(dataPath(""));
8.   // convert to lowercase
9.   for (int i = 0; i < kickFile.length; i++)
10.     kickFile[i] |= 96;
11.   // Save to a tempoaray file
12.   saveBytes("/data/temp.txt", kickFile );
13.   // Delete original and rename temp
14.   File org = new File(dataPath(""), "kick.txt");
15.   File temp = new File(dataPath(""), "temp.txt");
16.   println(org + "  " + boolText(org.exists()));
17.   println(temp + "  " + boolText(org.exists()));
18.   println(org.delete());
19.   println(temp.renameTo(org));
20. }
21. 
    
22. String boolText(boolean b){
23.   return (b ? "true" : "false");
24. }

Hi

The problem appears to be a bug in Processing in that it does not close the input stream in loadBytes so causing the file to be locked.

I have raised an issue

Hi quarks