请帮助我理解这一行代码

Question

CSVParser csvParser = null;
String csvFilename = "C:\\Users\\ITEM.txt20141022";


csvParser = new CSVParser(new BufferedReader(new FileReader(csvFilename)), CSVFormat.newFormat('|'));

The algorithm as far as I understand it:

1. The FileReader object is passed to the BufferedReader constructor.
2. The BufferedReader object is passed to the CSVParser constructor. This would be one of the two parameters passed to the csvParser?
3. the second csvParser parameter is CSVFormat.newFormat('|')

Would this line be considered two parameters that are passed to the csvParser Object? These two parameters are then used in the csvParser constructor? I have looked at the javadocs and am failing to understand how all these pieces fit together to instantiate the CSVParser. How would you know this is possible in the first place? I have been taking a beginner java class for a couple of weeks now and I've never seen anything like this. Could someone please explain to me how this line works as if you were talking to a 5 year old.

Answer 1

You have it correct, as near as I can tell.

This programmer is invoking constructors in place of declaring objects of correct type, instantiating objects to put in the object variables, and then using the variables. It could also be written as:

CSVFormat format = CSVFormat.newFormat('|');
FileReader reader = new FileREader(csvFilename);
BufferedReader bReader = new BufferedReader(reader);
CSVParser parser = new CSVParser(bReader, format);

I'm assuming the type returned by the first method call.

Hope that's more clear. It's how I would have written it...

Answer 2

CSVParser constructor takes two arguments as below:

CSVParser(Reader reader, CSVFormat format)

Now follow the code carefully, should be easy to understand, take care of the parentheses