Question

Thanks Marko. I rewrite the code. try to make it simple. this time it can really compile. but it can only delete duplicate items sit next to each other. for example, if i put in 1 2 3 3 4 4 5 1 — the output is 1 2 3 4 5 1. it can’t pick up the duplicate at the end.
(BTW: new to this website, if make any display mess my apologies)

here’s the new code:

import java.util.*;

public class SetListDemo{
public static void main(String[] args){
    SetListType newList = new SetListType();
    Scanner keyboard = new Scanner(System.in);

    System.out.println( "Enter a series of items: ");
        String input = keyboard.nextLine();

    String[] original = input.split(" ");
    for (String s : original)
    newList.insert(s);

    List<String> finalList = new ArrayList(Arrays.asList(original)) ;

    Iterator<String> setIterator = finalList.iterator();  

    String position = null;

    while(setIterator.hasNext()){
        String secondItem = setIterator.next();

        if(secondItem.equals(position)){
            setIterator.remove();
        }   

        position = secondItem;
    }

    System.out.println("\nHere is the set list:");
    displayList(finalList);
    System.out.println("\n");
}

public static void displayList(List list){
    for(int index = 0; index <list.size(); index++)
    System.out.print(list.get(index) + ", ");
}

}

Answer 1

To answer the question “delete duplicates in java arraylist”:

Just put all elements into a Set and you’re done.

-or-

Iterate your original list and add the elements to a List, but before adding them, check with List#contains() if the element is already there.

EDIT: Try this:

String[] original = input.split(" ");
List<String> finalList = new ArrayList<String>();

for (String s : original) {
    if (!finalList.contains(s)) {
        finalList.add(s);
    }
}

System.out.println("\nHere is the set list:");
displayList(finalList);
System.out.println("\n");