What is the best way to generate a unique and short file name in Java

Question

I don\'t necessarily want to use UUIDs since they are fairly long.

The file just needs to be unique within its directory.

One thought which comes to mind is

Answer 1

    //Generating Unique File Name
    public String getFileName() {
        String timeStamp = new SimpleDateFormat("yyyy-MM-dd_HH:mm:ss").format(new Date());
        return "PNG_" + timeStamp + "_.png";
    }