file delete and rename not working

Question

Here is the code but it does not delete storedIp file and rename tempFile to storedIP. Both file exist

               String host=ipParsing(hostName);
               File tempFile= new File("tempFile.txt");
               File strFile = new File("StoredIp.txt");
        BufferedReader bufferReader = new BufferedReader( new FileReader(strFile));
        BufferedWriter bw = new BufferedWriter(new FileWriter(tempFile));
                String line;
        while ((line = bufferReader.readLine()) != null)   {
             if(host.equals(line))
                        {
                            found=true;
                            line="";
                        }
                            bw.write(line);
                        if(!line.equals(""))
                            bw.newLine();
                  }
       bw.close();
       bufferReader.close();
               strFile.delete();
               tempFile.renameTo(new File ("StoredIP.txt"));

Answer 1

Well, a call to File.delete() does not necessary delete the file. As the JavaDoc says: be sure to check the return value.

Ignoring this (like you did) is a common source of errors.

Answer 2

One occasion where this delete/renameTo easily goes awry, is when the files are in use . A solution seen consists of using an additional lock file. Too complicated for such a simple thing.

Using an embedded database , like java's own Derby, which is not that difficult. The database needs no extra provision. There are good tutorials with simple example code.