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 );}
    }

}

}

kai · Accepted Answer · 2014-02-13T11:38:25.013

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

Just be aware that `SubList` is not an independent entity. https://stackoverflow.com/a/17899947/8219923 — Baudev, Jun 29 '18 at 13:56

Zeeshan · Answer 2 · 2014-02-13T11:38:45.910

3

Problem is in your code:

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

The get method of class ArrayList accepts only one argument, here you are passing two.

You can use subList(int fromIndex, int toIndex) to get your desired result.

edited Feb 13 '14 at 11:38

answered Feb 13 '14 at 11:30

Zeeshan

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You can use the method subList as explained by kai – Zeeshan Feb 13 '14 at 11:41

score 1 · Answer 3 · answered Feb 13 '14 at 11:26

You can take range of values by index from ArrayList as follows.

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

    for(int i=0;i<4;i++){
      if(i<=2 && i>=1){
          System.out.println(list.get(i));
      }
    }

score 1 · Answer 4 · answered Feb 13 '14 at 11:30

1

i would do it like that

if (idSt1 < idSt2 && idSt2 < idSt3) {
            for (int j = idxID1-3; j < idxID2-3; j++){
                System.out.println(ArrayData.get(j));
            }

        }

answered Feb 13 '14 at 11:30

tr4pt

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

4 Answers4