CODEWITHSUNDEEP
javasearchfilterarraylist
Krishnabhadra
Krishnabhadra

Reputation: 34275

Java integer ArrayList return elements within a specific range

I am having a java ArrayList of integer

ArrayList <Integer> ageList  = new ArrayList <Integer>();

I am having some integer values in this arrayList. I want to create a new ArrayList which has all elements in the above arrayList which passes a condition, like value between 25 and 35. ie if my ageList contains values

{12,234,45,33,28,56,27}

my newList should contain

{33,28,27}

How can I achieve this?

Note: I came to java from objective C background, where I used NSPredicate to easly do such kind of things..Any similiar methods in java?

Upvotes: 3

Views: 12497

Answers (7)

user219882
user219882

Reputation: 15844

You may use foreach loop

List<Integer> newList = new ArrayList<Integer>();
for (Integer value : ageList) {
    if (value >= 25 && value <= 35) {
        newList.add(value);
    }
}

Upvotes: 6

z3pr4h
z3pr4h

Reputation: 196

Try this:

ArrayList<Integer> newList = new ArrayList<Integer>(ageList);
for (Iterator<Integer> it = newList.iterator(); it.hasNext();) {
    int n = it.next();
    if (n < 25 || n > 35)
      it.remove();
}

Upvotes: 4

aioobe
aioobe

Reputation: 420971

There is no "filter" facility in the standard API. (There is in Guava and Apache Commons however.) You'll have to create a new list, loop through the original list and manually add the elements in range 25-35 to the new list.

If you have no intention to keep the original list, you could remove the elements out of range using an Iterator and the Iterator.remove method.

If you have no duplicates in your list, you could use a TreeSet in which case you could get all elements in a specific range using headSet / tailSet.

Related question: (possibly even a duplicate actually)

Upvotes: 7

Mister Smith
Mister Smith

Reputation: 28168

Not possible with the standard JCF. You'll have to iterate.

Consider using Guava. It has such kind of utilities.

http://code.google.com/p/guava-libraries/

Upvotes: 1

Harry Joy
Harry Joy

Reputation: 59660

No there is no built in functionality in java [AFAIK].

The steps can be:

  1. Loop through ageList.
  2. Check for condition.
  3. If condition is success then add that element to new list or else do nothing.

Sample code:

    List<Integer> ageList = new ArrayList<Integer>();
    //-- add data in ageList

    List<Integer> newList = new ArrayList<Integer>();
    for (Integer integer : ageList) {
        if(integer >= 25 && integer <= 35)
            newList.add(integer);
    }

Upvotes: 1

Jon Skeet
Jon Skeet

Reputation: 1500495

Well, with Guava you could write:

Iterable<Integer> filtered = Iterables.filter(list, new Predicate<Integer>() {
    @Override public boolean apply(Integer value) {
        return value >= 25 && value <= 35;
    }
});
List<Integer> newList = Lists.newArrayList(filtered);

Upvotes: 6

Charles Goodwin
Charles Goodwin

Reputation: 6642

Iterate over it and just add the ones that match? It's 3 lines of code... 4 including the new ArrayList declration.

Upvotes: 0

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