ArrayList, Getting values, from index() to index()

Question

Hi everybody I am trying to get values from an ArrayList I created. I have some indexes, and I want to print the data ONLY between the indexes I want, so far I ave done this, but it does not seem to work. I think the get() is not valid for want I want... Any ideas?

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

    Scanner dataSc = new Scanner(new FileReader("StudData1.txt"));

    ArrayList<String> ArrayData = new ArrayList<String>();
    ArrayList<String> idData = new ArrayList<String>();
    ArrayList<String> idIndex = new ArrayList<String>();

    int b = 0;
    int a = 0;
    int i = 0;

    while (dataSc.hasNextLine()) {
        String data = dataSc.nextLine();
        ArrayData.add(i, data);

        if (data.contains("ID: ")) {
            idData.add(a, data);
            idData.set(a, (idData.get(a).replaceAll("[\\D]", "")));

            a++;
            b++;
        }

        i++;
        idIndex.add(b, Integer.toString(i));
    }

    int idSt1 = Integer.parseInt(idData.get(0));
    int idSt2 = Integer.parseInt(idData.get(1));
    int idSt3 = Integer.parseInt(idData.get(2));

    int idxID1 = Integer.parseInt(idIndex.get(0));
    int idxID2 = Integer.parseInt(idIndex.get(1));
    int idxId3 = Integer.parseInt(idIndex.get(2));

    if (idSt1 < idSt2 && idSt2 < idSt3) {

         System.out.println(ArrayData.get(idxID1-3 , idxID2-3 );}
    }

}

}

Answer 1

Its easy done with a for-loop.

    for(int i = startindex+1; i<endindex; i++) {
        System.out.println(ArrayData.get(i));
    }

This loop will print all objects in the arraylist that are between the given indices. But there is no method called get() which returns a collection of items that are between to given indices, you can only use the subList(arg0, arg1) method to creat a subcollection and then iterate over this subcollection. Take a look at the Docs http://docs.oracle.com/javase/6/docs/api/java/util/ArrayList.html#get%28int%29

Example:

    List<String> al = new ArrayList<>();
    al.add("a");
    al.add("b");
    al.add("c");
    al.add("d");

    List<String> sublist = al.subList(0, 3);  //inclusive index 0, exclusive index 3

    for(String s : sublist)
        System.out.println(s);

Output: a, b, c