CODEWITHSUNDEEP
javaarraylist
Heneko
Heneko

Reputation: 81

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

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 );}
    }

}

}

Upvotes: 6

Views: 28843

Answers (4)

Zeeshan
Zeeshan

Reputation: 12421

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.

Upvotes: 3

kai
kai

Reputation: 6887

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

Upvotes: 10

tr4pt
tr4pt

Reputation: 317

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));
            }

        }

Upvotes: 1

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35557

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));
      }
    }

Upvotes: 1

Related Questions