how can we remove multiple values in arrayList?

Question

remove method we used for single remove, but I want to delete multiple values in array List.

ArrayList<Integer> al=new ArrayList<Integer>();
    al.add(7);
    al.add(8);
    al.add(9);
    al.add(13);
    al.add(22);
    al.add(55);
    al.add(88);
    //adding values
    for(int i=0;i<100;i++){
        al.add(i);
    }

I added duplicate elements, I want to fetch the duplicate elements and remove it from arraylist

for example:

output like:1, 2, 3, 4, 5, 6, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100

yeah but i want duplicate elements. that elements not present in my output — venkat, Oct 16 '18 at 08:57
Why are you doing this? (i.e. what is the bigger picture) and will you always know the range you want? (i.e. 1 to 100) — Lio Elbammalf, Oct 16 '18 at 08:59
A possible duplicate of https://stackoverflow.com/questions/203984/how-do-i-remove-repeated-elements-from-arraylist — Siddhivinayak Shanbhag, Dec 05 '18 at 05:33

Ori Marko · Accepted Answer · 2018-10-16T09:15:05.797

3

Use two ArrayLists, one with objects to remove and use removeAll method:

Removes from this list all of its elements that are contained in the specified collection.

ArrayList<Integer> toRemove=new ArrayList<>();//use diamond operator to reduce verbosity 
toRemove.add(7);
toRemove.add(8);
toRemove.add(9);
toRemove.add(13);
toRemove.add(22);
toRemove.add(55);
toRemove.add(88);
ArrayList<Integer> al=new ArrayList<>();
for(int i=0;i<100;i++){
    al.add(i);
}
al.removeAll(toRemove);

edited Oct 16 '18 at 09:15

answered Oct 16 '18 at 09:02

Ori Marko

56,308
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can u explain briefly – venkat Oct 16 '18 at 09:06
@Venkatesh added more details, one list holds objects to remove and the full list remove all the objects using `removeAll` method – Ori Marko Oct 16 '18 at 09:07
@ user7294900 Thankyou – venkat Dec 11 '18 at 11:56

score 2 · Answer 2 · edited Dec 05 '18 at 07:49

ArrayList<Integer> al=new ArrayList<Integer>();     
ArrayList<Integer> remove=new ArrayList<Integer>();   
al.add(7);   
al.add(8);   
al.add(9);   
al.add(13);     
al.add(22);   
al.add(55);  
al.add(88);  
remove.add(7);   
remove.add(8);   
remove.add(9);   
remove.add(13);   
remove.add(22);   
remove.add(55);   
remove.add(88);   
//adding values   
for(int i=0;i<100;i++){   
    al.add(i);   
}   
al.removeAll(remove);  
System.out.println(al);

score 1 · Answer 3 · answered Oct 16 '18 at 09:00

1

ArrayList<Integer> withoutDuplicates = new ArrayList<>(new HashSet<>(al));

Does not affect the original list with duplicates, which is what you seem to be asking for. If you do not care about the structure used for the second collection you could just keep it as a Set without creating another ArrayList.

answered Oct 16 '18 at 09:00

adickinson

553
1
3
14

"i want fetch the duplicate elements and remove it from arraylist" -> I'm confused, you asked here to remove duplicate elements, did you mean to remove BOTH values if more than one for a given number exists? – adickinson Oct 16 '18 at 09:14

score 0 · Answer 4 · answered Oct 16 '18 at 08:59

Make use of streams to get distinct value. However i still believe Sets perfectly suit this scenario.

    ArrayList<Integer> al=new ArrayList<Integer>();
        al.add(7);
        al.add(8);
        al.add(9);
        al.add(13);
        al.add(22);
        al.add(55);
        al.add(88);

    List<Integer> list = al.stream().distinct().collect(Collectors.toList());
System.out.println(list);

how can we remove multiple values in arrayList?

4 Answers4