如何解析具有多个键值对的CSV？

Question

I have a CSV in this format:

"Account Name","Full Name","Customer System Name","Sales Rep"

"0x7a69","Mike Smith","0x7a69","Tim Greaves"

"0x7a69","John Taylor","0x7a69","Brian Anthony"

"Apple","Steve Jobs","apple","Anthony Michael"

"Apple","Steve Jobs","apple","Brian Anthony"

"Apple","Tim Cook","apple","Tim Greaves"

...

I would like to parse this CSV (using Java) so that it becomes:

"Account Name","Full Name","Customer System Name","Sales Rep"

"0x7a69","Mike Smith, John Taylor","0x7a69","Tim Greaves, Brian Anthony"

"Apple","Steve Jobs, Tim Cook","apple","Anthony Michael, Brian Anthony, Tim Greaves"

Essentially I just want to condense the CSV so that there is one entry per account/company name.

Here is what I have so far:

String csvFile = "something.csv";
String line = "";
String cvsSplitBy = ",";

List<String> accountList = new ArrayList<String>();
List<String> nameList = new ArrayList<String>();
List<String> systemNameList = new ArrayList<String>();
List<String> salesList = new ArrayList<String>();

try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) 
    {

        while ((line = br.readLine()) != null) {

            // use comma as separator
            String[] csv = line.split(cvsSplitBy);

            accountList.add(csv[0]);
            nameList.add(csv[1]);
            systemNameList.add(csv[2]);
            salesList.add(csv[3]);

        }

So I was thinking of adding them all to their own lists, then looping through all of the lists and comparing the values, but I can't wrap my head around how that would work. Any tips or words of advice are much appreciated. Thanks!

Answer 1

By analyzing your requirements you can get a better idea of the data structures to use. Since you need to map keys (account/company) to values (name/rep) I would start with a HashMap . Since you want to condense the values to remove duplicates you'll probably want to use a Set .

I would have a Map<Key, Data> with

public class Key {
    private String account;
    private String companyName;

    //Getters/Setters/equals/hashcode
}

public class Data {
    private Key key;
    private Set<String> names = new HashSet<>();
    private Set<String> reps = new Hashset<>();

    public void addName(String name) {
        names.add(name);
    }

    public void addRep(String rep) {
        reps.add(rep);
    }

    //Additional getters/setters/equals/hashcode
}

Once you have your data structures in place, you can do the following to populate the data from your CSV and output it to its own CSV (in pseudocode)

    Loop each line in CSV
      Build Key from account/company
      Try to get data from Map
      If Data not found
        Create new data with Key and put key -> data mapping in map
      add name and rep to data

    Loop values in map
      Output to CSV

Answer 2

Well, I probably would create a class, let's say "Account", with the attributes "accountName", "fullName", "customerSystemName", "salesRep". Then I would define an empty ArrayList of type Account and then loop over the read lines. And for every read line I just would create a new object of this class, set the corresponding attributes and add the object to the list. But before creating the object I would iterate overe the already existing objects in the list to see whether there is one which already has this company name - and if this is the case, then, instead of creating the new object, just reset the salesRep attribute of the old one by adding the new value, separated by comma.

I hope this helps :)