protected File writeToTempFile(File dir, Address logical_addr, Address physical_addr, String logical_name) throws Exception {
        DataOutputStream out=null;
        File file=null;
        String filename=null;
        try {
            file=File.createTempFile("temp", null, dir);
^^ If this fails, then file is null and delete is called with null
            filename=file.getName();
...
        }
        catch(Exception e) {
            Util.close(out);
            log.error(Util.getMessage("FailedToWriteTemporaryFile") + filename, e);
            deleteFile(file);
            return null;
        }