Create an ArrayList of unique values [duplicate]

Question

I have an ArrayList with values taken from a file (many lines, this is just an extract):

20/03/2013 23:31:46 6870    6810    6800    6720    6860    6670    6700    6650    6750    6830    34864   34272 20/03/2013 23:31:46 6910    6780    6800    6720    6860    6680    6620    6690    6760    6790    35072   34496 

Where the first two values per line are strings that contain data and are stored in a single element.

What I want to do is compare the string data elements and delete, for example, the second one and all the elements referred to in that line.

For now, I've used a for loop that compares the string every 13 elements (in order to compare only data strings).

My question: can I implement other better solutions?

This is my code:

import java.util.Scanner; import java.util.List; import java.util.ArrayList; import java.io.*; import java.text.SimpleDateFormat; import java.util.Date;  public class Main {     public static void main(String[] args) throws Exception{          //The input file         Scanner s = new Scanner(new File("prova.txt"));          //Saving each element of the input file in an arraylist          ArrayList<String> list = new ArrayList<String>();         while (s.hasNext()){             list.add(s.next());         }         s.close();          //Arraylist to save modified values         ArrayList<String> ds = new ArrayList<String>();          //         int i;         for(i=0; i<=list.size()-13; i=i+14){              //combining the first to values to obtain data               String str = list.get(i)+" "+list.get(i+1);             ds.add(str);             //add all the other values to arraylist ds             int j;             for(j=2; j<14; j++){                 ds.add(list.get(i+j));             }              //comparing data values             int k;               for(k=0; k<=ds.size()-12; k=k+13){                 ds.get(k); //first data string element                   //Comparing with other strings and delete                 //TODO               }         }     } } 

Answer 1

Try checking for duplicates with a .contains() method on the ArrayList, before adding a new element.

It would look something like this

   if(!list.contains(data))        list.add(data); 

That should prevent duplicates in the list, as well as not mess up the order of elements, like people seem to look for.

Answer 2

Create an Arraylist of unique values

You could use Set.toArray() method.

A collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element. As implied by its name, this interface models the mathematical set abstraction.

http://docs.oracle.com/javase/6/docs/api/java/util/Set.html