Inserting values in LinkedHashMap without using the key

Question

I have a table data in CSV format. First row contains all column names(keys) and all subsequent rows are records(values) as shown below:

ID,Name,Contact,Address
1,Alex,987654321,CA USA
2,Bob,4489398,LA USA
3,Marley,7236487,Washington

I am reading this file and trying to store the records as key value pair in LinkedHashMap. Here is my code to show what I am trying to do. My question is written in the code as comment.

public static void readCSV() throws IOException {

    BufferedReader br = new BufferedReader(new FileReader("table.csv"));

    Map<String, ArrayList<String>> map = new LinkedHashMap<>();

    String line = br.readLine();
    String[] keys = line.split(",");

    /*insert all keys with a corresponding empty arraylist as value to store
    all values of a particular key. ie each arralist will contain all values
    of individual columns. Since it is a linkedhashmap, keys are stored in 
    same order as they appear in the csv file*/

    for (String key : keys) {
        map.put(key, new ArrayList<String>());
    }

    while((line = br.readLine())!=null){
        String[] values = line.split(",");

        for (String value : values) {

            /*here I want to get the arraylists sequentially to store value.
            I know the first value goes in the first arraylist, second goes
            to second arraylist and so on.

            Is there a way to do this without using the key here??
            */

        }
    }
}

Why this data structure and not a map key -> columnIndex and a list of String[] (one per row)? — fabian
– fabian, Commented Jun 23, 2016 at 7:32
It could be better to parse every row to a custom object and put them into a list. — davioooh
– davioooh, Commented Jun 23, 2016 at 7:42

Eran · Accepted Answer · 2016-06-23 07:29:18Z

1

You can use an Iterator to iterate over the values of your Map :

while((line = br.readLine())!=null){
    String[] values = line.split(",");

    Iterator<ArrayList<String>> iter = map.values().iterator ();
    for (String value : values) {

        if (iter.hasNext()) {
            iter.next().add(value);
        }

    }
}

answered Jun 23, 2016 at 7:29

Eran

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