code: private static final void checkTempDirs(final String[] tempDirs) throws Exception {
  
  		for (int i = 0; i < tempDirs.length; ++i) {
  
  			final String dir = tempDirs[i];
  			if (dir == null) {
  				throw new Exception("Temporary file directory #" + (i + 1) + " is null.");
  			}
  
  			final File f = new File(dir);
  
  			if (!f.exists()) {
  				throw new Exception("Temporary file directory '" + f.getAbsolutePath() + "' does not exist.");
  			}
  
  			if (!f.isDirectory()) {
  				throw new Exception("Temporary file directory '" + f.getAbsolutePath() + "' is not a directory.");
  			}
  
  			if (!f.canWrite()) {
  				throw new Exception("Temporary file directory '" + f.getAbsolutePath() + "' is not writable.");
  			}
  		}
  	}
docs: Checks, whether the given strings describe existing directories that are writable. If that is not
  the case, an exception is raised.
  
  @param tempDirs
  An array of strings which are checked to be paths to writable directories.
  @throws Exception
  Thrown, if any of the mentioned checks fails.