I have a requirement where I have key value pairs (key, value). There can be lakhs of such key value pairs. I need to decide upon an approach, whether i should store these in a normal text file or a XML file. I will have to read these (key, value) pairs from the file (text or XML or any other file format) form a HashMap and save these values to database.
Which approach is better storing in text file, then again reading through lakhs of records, tokenize on ',' and form the hashmap, or have a XML file with key value nodes and parse it and form hashmap. Also is it better to have properties file and have use java Properties api.
I cant see what a HashMap has to do with the problem.
IF you have more key-value pairs than will fit in memory as a hashmap THEN a database will have to be used.
IF your hashmap fits in memory you can serialize it to disk as a serialized Java object - this is surprisingly fast.
It seems to me that the choice between a properties style line by line text file and XML depends on how you are going to edit the file. Having said that, parsing the properties style will be LOTS faster.