CODEWITHSUNDEEP
javaarraysobject2d
user1093111
user1093111

Reputation: 1111

Is there a way to dynamically create Objects?

I have a homework problem to calculate delayed flights of different airplane carriers. I am reading from a CSV file and have create a class for "carriers" with total flights and delayed flights. Since there is many carriers (10 or so), how can I create carrier objects as they are read from the CSV (or a 2d array).

Instead of 

carrier UA = new carrier("Us Airways", 100, 50);
carrier Delta = new carrier("Delta", 100, 50);

and hard coding all the objects.

right now the CSV data is in a 2D array, and the non object oriented code is as follows.

    public static void main (String [] args) throws Exception{

    CSVReader reader = new CSVReader(new FileReader("delayed.csv"));
    String [] nextLine;

    String[][] flightData = new String[221][3];
    int i=0;    
        while ((nextLine = reader.readNext()) != null) {

            for(int r = 0; r<2; r++){
            flightData[i][0] = nextLine[1];
            flightData[i][1] = nextLine[6];
            flightData[i][2] = nextLine[7];
            }
        i++;
        //System.out.println("Carrier: " + nextLine[1] + "\t\tTotal: " + nextLine[6] + "\t\tDelayed: " + nextLine[7] + "");
        }
        while(flightData != null){
        carrier 
        }
}

thanks.

Upvotes: 0

Views: 306

Answers (1)

Majid Laissi
Majid Laissi

Reputation: 19778

List<Carrier> listCarrier = new ArrayList<Carrier>();      

while ((nextLine = reader.readNext()) != null) {

    listCarrier.add(new Carrier(nextLine[1], Integer.valueOf(nextLine[6]), Integer.valueOf(nextLine[7])));

}

Note that the class Carrier should start with an uppercase.

If you want to avoid dupplicates, you can use HashMap instade of ArrayList as follows:

Map<String, Carrier> listCarrier = new HashMap<String, Carrier>();

In order to insert a new record, use:

Carrier carrier = new Carrier(nextLine[1], Integer.valueOf(nextLine[6]), Integer.valueOf(nextLine[7]));
listCarrier .put(nextLine[1],carrier );
//Here the key is the carrier name, and the value is the carrier object

If you have dupplicate carriers with same name but different values, only the last one will be kept in the HashMap.

To get a carrier from the list, use:

listCarrier.get("carrier_name")

And this would return the carrier with name "carrier_name" from the Map, if available.

Upvotes: 1

Related Questions