Java: Iterating through an Array List

Question

I have an ArrayList containing names of instantiated objects that I want to execute the method 'count' on. I'm unsure if/how to do that, though. I have a loop to scan through the array list, and added pseudocode with what I'm trying to achieve.

    n = 0;
    while(n <= arrayList.size()){
        (arrayList.get(n)).count();
    }

I'm new to java and am not sure this is possible, but any help would be appreciated. Thanks.

Wait, the list contains objects that support the method count(), right? What did you mean by containing names of instantiated objects? — raffian
– raffian, Commented Aug 28, 2013 at 1:54
Names as strings. I.e. "kiwi" would be an object that could execute kiwi.count. I got a good answer from raffian though. — user2720349
– user2720349, Commented Aug 28, 2013 at 2:04

raffian · Accepted Answer · 2013-08-28 01:52:55Z

3

Simpler way to do it...

ArrayList<MyObject> list = ...
for( MyObject obj : list)
  obj.count()

answered Aug 28, 2013 at 1:52

raffian

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Comments

luoluo · Accepted Answer · 2013-08-28 03:39:48Z

1

You have several ways to do so:

Basic1:

n = 0;
while (n < arrayList.size()) {
    (arrayList.get(n)).count();
    n++;
}

Basic2:

for (int i = 0; i < arrayList.size(); i++) {
    (arrayList.get(i)).count();
}

Better1:

for(ClassTypeOfArrayList item: arrayList) {
    item.count();
}

Better2:

Iterator iterator = arrayList.iterator();
while(iterator.hasNext()){
    System.out.println(iterator.next());
}

edited Aug 28, 2013 at 3:39

answered Aug 28, 2013 at 2:37

luoluo

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2 Comments

nachokk Over a year ago

you forget the OO way , for(Iterator it = arrayList.iterator();it.hasNext();){ Object o= it.next();} or with a while

luoluo Over a year ago

In fact I viewed this problem at the point of a green hand. If you are new to java, using the first two is a fast way to get thing done. When you are familiar with java you may do anything you what. Thx.

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