how to check if all elements of java collection match some condition?

Question

I have an ArrayList<Integer>. I want to check if all elements of the list are greater then or less then certain condition. I can do it by iterating on each element. But I want to know if there is any method in Collection class to get the answer like we can do to find maximum or minimum with Collections.max() and Collections.min() respectively.

If i'm not wrong, Collections.max() and Collections.min() also iterate through each element. — Kartik_Koro, Jun 19 '14 at 10:19
`max` and `min` make no sense per se, because `Collection` is a generic type. for instance if you have `Collection — logoff, Jun 19 '14 at 10:20

score 61 · Accepted Answer · edited Jun 19 '14 at 10:23

61

If you have java 8, use stream's allMatch function (reference):

 ArrayList<Integer> col = ...;
 col.stream().allMatch(i -> i>0); //for example all integers bigger than zero

edited Jun 19 '14 at 10:23

logoff

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answered Jun 19 '14 at 10:18

kajacx

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Didn't know about this, seems useful! :D – Kartik_Koro Jun 19 '14 at 10:20
very useful..something new to me..Thanks – Chirag Jun 19 '14 at 10:21
I am not getting how to use this predicate and pass it in to argument. Can anyone give me demo ? – Chirag Jun 19 '14 at 11:51
1

Still useful and saves lives four years later :D – Stanislav Codes Oct 17 '18 at 01:21
Should probably be noted that the above solution will return true for an empty list. – stackbacker Jul 13 '23 at 15:09

score 8 · Answer 2 · answered Jun 19 '14 at 10:38

8

You can use Google guavas Iterables.all

 Iterables.all(collection, new Predicate() {
    boolean apply(T element)  {
       .... //check your condition 
   } 
 }

answered Jun 19 '14 at 10:38

amorfis

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score 0 · Answer 3 · edited Jun 19 '14 at 10:23

0

You cannot check values without iterating on all elements of the list.

for(Integer value : myArrayList){

    if(value > MY_MIN_VALUE){
        // do my job
    }
}

I hope this will help

edited Jun 19 '14 at 10:23

JoaoFilipeClementeMartins

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answered Jun 19 '14 at 10:21

Pracede

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I want to do my job only if all elements of list > of my condition – Chirag Jun 19 '14 at 10:23

score 0 · Answer 4 · answered Jun 21 '23 at 11:26

The answer col.stream().allMatch is the best solution for the original task, i.e. to check if all elements fulfill some condition.

If you instead want to find the min or max int value of a Stream/Collection you must first convert it to an IntStream using col.stream().mapToInt(ToIntFunction) where the ToIntFunction can be MyObject::getIntvalue or o -> o.getIntValue() or Integer::intValue if you already have a List<Integer> as explained on How do I get an IntStream from a List<Integer>?

how to check if all elements of java collection match some condition?

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