Modifying complex csv files in java

Question

I wanted to write a program which can print, and modify the irregular csv files. The format is as follows:

    1.date
    2.organization name
    3. student name         


        

Answer 1

Try uniVocity-parsers to handle this. For parsing this sort of format, you'll find a few examples here. For writing, look here and here.

Adapting from the examples I've given, you could write:

final ObjectRowListProcessor dateProcessor = new ObjectRowListProcessor();
final ObjectRowListProcessor clubProcessor = new ObjectRowListProcessor();
final ObjectRowListProcessor memberProcessor = new ObjectRowListProcessor();

InputValueSwitch switch = new InputValueSwitch(0){
    public void rowProcessorSwitched(RowProcessor from, RowProcessor to) {
    //your custom logic here
    if (to == dateProcessor) {
        //processing dates.
    }
    if (to == clubProcessor) {
        //processing clubs.
    }
    if (to == memberProcessor){
        //processing members
    }
};

switch.addSwitchForValue("1.", dateProcessor, 1);  //getting values of column 1 and sending them to `dateProcessor`
switch.addSwitchForValue("2.", clubProcessor, 1); //getting values of column 1 and sending them to `clubProcessor`
switch.addSwitchForValue("3.", memberProcessor, 1, 2, 3); //getting values of columns 1, 2, and 3 and sending them to `memberProcessor` 
setDefaultSwitch(memberProcessor, 1, 2, 3); //Rows with blank value at column 0 are members. Also get columns 1, 2, and 3 and send them to `memberProcessor`

CsvParserSettings settings = new CsvParserSettings(); //many options here, check the tutorial and examples

// configure the parser to use the switch
settings.setRowProcessor(switch);

//creates a parser
CsvParser parser = new CsvParser(settings);

//parse everying. Rows will be sent to the RowProcessor of each switch, depending on the value at column 0.
parser.parse(new File("/path/to/file.csv")); 

Disclaimer: I'm the author of this library, it's open-source and free (Apache 2.0 license)