Question

I’ve got a text file with dats for three people. The properties for each person is separated by a comma. It looks like this:

Patrick, Gary, Male, Blue, 1/28/1948
Carson, Larry, Male, Pink, 11/24/1976
Fisher, Paul, Male, Orange, 5/12/1995

What I’m trying to accomplish ultimately to to sort those people by their last name in ascending order.

Not sure I’m thinking about this the right way, but I wanted to create a 2D array that would assign each property to the proper row and column. We can forget about the sorting for now.

How can I get each line to populate a row of the array, with each separate property in its own column?

Maybe I should just be reading the file line by line, then adding each character to a 2D array using lineFromFile.charAt(index) to populate or something like that? Any sample suggestions would be greatly appreciated.

Answer 1

String.split() can be of help here:

person[i] = line.split(", ");

But what you probably really want is to abandon the idea of a 2-D array and create a List of Persons, where Person is a class that you define.

public class Person {
  public final String firstName;
  public final String lastName;
  public final String birthDate; //should really be a java.util.Date
  //...plus a constructor for the above
}

//...
List<Person> people = new ArrayList<Person>();
String line = reader.readLine();
String[] fields = line.split(", ");
people.add(new Person(fields[0], fields[1], /*...*/));

A 2D array almost always suggests that you need a class to represent a “row” of data.

Sorting becomes very easy too:

//sorts the people in descending order by first name
people.sort(new Comparator<Person>() {
    public int compare(Person a, Person b) {
       b.firstName.compareTo(a.firstName);
    }
});