is there any method to delete duplicate in linkedlist have I tried a method but it gives me index out of bounds exception?

Question

import java.util.*;

public class list<E> extends LinkedList<E> {
  int j=0;
  int l=0;
  LinkedList Search(Object o) {
    int[] array=new int[super.size()];
    for(int i=0; i<super.size(); i++) {
        if(o.equals(super.get(i))) {
            array[j]=i;
            j=j+1;
            continue;
        }
    }
    return Arrayfilter(array);
 }

 private LinkedList Arrayfilter(int[] i) {
    int[] aray=null;
    LinkedList<Integer> ll= new LinkedList<Integer>();
    for(int j:i){
        if((l==0)|(j!=0)){
            ll.add(j);
            l=l+1;
            continue;
        }
    }
    return ll;
 }

 boolean deleteduplicate() {
    for(int l=0; l<super.size(); l++){
      for(int i:Search(super.get(l))) {
        super.remove(i);
      }
    }
    return true;
 }
}

Whenever I tried that method delete duplicate () it gives me index out of bounds error how I can modify the method that it return true

I know that whenever I remove anything in for loop I reducing the size of list that giving me that error, or anything else?

Does this answer your question? [What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?](https://stackoverflow.com/questions/5554734/what-causes-a-java-lang-arrayindexoutofboundsexception-and-how-do-i-prevent-it) — akuzminykh, Jun 03 '20 at 11:47
1.) You are using the [*raw type* `LinkedList`](https://stackoverflow.com/q/2770321/2711488) several times. 2) You are notoriously using the opposite of the common coding style, lowerclass class names and upper case method names. This makes the code hard to read for those who want to help you. 3) You may rethink [whether `LinkedList` is the right choice](https://stackoverflow.com/q/322715/2711488) here. 4.) This brings us to one of the reasons you should [*use* collections, not subclass them](https://stackoverflow.com/q/49002/2711488). — Holger, Jun 03 '20 at 16:29

fjsv · Accepted Answer · 2020-06-03T13:09:29.690

2

If you use LinkedHashSet<E> instead of LinkedList you get that for free.

To keep your code you could use:

void deleteduplicate() {
   Set<E> tmp = new LinkedHashSet<>(this);
   this.clear();
   this.addAll(tmp);
}

Following the example in [this question].(How do I remove repeated elements from ArrayList?)

edited Jun 03 '20 at 13:09

answered Jun 03 '20 at 11:48

fjsv

705
10
23

Thanks .. I am going to use that but .is it possible declare that method in linkedlist just wondering how? – Siddharth Rout Jun 03 '20 at 11:52
Thanks.. linkedhashset also work and order not changed t – Siddharth Rout Jun 03 '20 at 12:50
Ah. The order would change with HashSet, but you can just change it to LinkedHashSet and get the same result but ordered. Updated – fjsv Jun 03 '20 at 13:07

Debapriya Biswas · Answer 2 · 2020-06-05T18:51:44.523

1

You can use a Set to track the duplicates and a listIterator() to traverse the linked list as below

   public LinkedList<E> deleteDuplicate(LinkedList<E>list)
     {
        Iterator<? extends E> it=list.listIterator();
        Set<E> set = new HashSet<>();
        while(it.hasNext())
        {
            E e=it.next();
            if(set.contains(e))
               it.remove();
            else
                set.add(e);
        }
        return list;
     }

EDIT :

public LinkedList<E> deleteDuplicate(LinkedList<E>list)
    {
        Iterator<? extends E> it=list.listIterator();
        Set<E> set = new HashSet<>();
        while(it.hasNext())
        {
            E e=it.next();
            if(!set.add(e))
                it.remove();
        }
        return list;
    }

edited Jun 05 '20 at 18:51

answered Jun 03 '20 at 12:16

Debapriya Biswas

1,079
11
23

2

The contract of `Set.add` is already sufficient to test the presence of an element, so you can simply use `while(it.hasNext()) if(!set.add(it.next())) it.remove();`, without a preceding `contains` test. Or do it even simpler: `Set set = new HashSet<>(); list.removeIf(e -> !set.add(e));`. – Holger Jun 04 '20 at 10:30
@Holger added in EDIT : section . Thanks – Debapriya Biswas Jun 05 '20 at 18:53

is there any method to delete duplicate in linkedlist have I tried a method but it gives me index out of bounds exception?

2 Answers2