adding arrayList to arraylist using loop

Question

Whenever i try and run my code i get an error array out of bounds.

    trans = new ArrayList<List<Transition>>(5);
    ArrayList<Transition> t = new ArrayList<Transition>(5);
    for (j = 0; j <5; j++)
        trans.get(j).addAll(t); // <- Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0

The capacity of a list is not its size. Your list is actually empty, and that's why you get the IndexOutOfBoundsException. — Chthonic Project
– Chthonic Project, Commented Nov 21, 2014 at 11:39

SMA · Accepted Answer · 2014-11-21 11:41:29Z

4

You have an empty list of size 0 when you create your list of lists and then you say get(i) which will try to compare size with i and jdk expect size to be greater than the index i.

So probably you could do something like:

trans = new ArrayList<List<Transition>>(5);
for (j = 0; j <5; j++) {
   trans.add(new ArrayList<Transition>()); 
}
ArrayList<Transition> t = new ArrayList<Transition>(5);
for (j = 0; j <5; j++)
    trans.get(j).addAll(t); // <- out of bounds

answered Nov 21, 2014 at 11:41

SMA

37.2k8 gold badges53 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

MihaiC · Accepted Answer · 2014-11-21 11:41:11Z

1

Your trans list is empty. You didn't add anything to it. When you run trans.get(j) it can't get anything.

answered Nov 21, 2014 at 11:41

MihaiC

1,5831 gold badge10 silver badges14 bronze badges

Comments

Maroun · Accepted Answer · 2014-11-21 11:41:01Z

0

See the docs:

Constructs an empty list with the specified initial capacity.

You didn't add anything, you cannot get:

 trans.get(j).addAll(t);
       ↑

Try to check the size, you'll get 0. So any attempt to access the trans will throw an exception.

answered Nov 21, 2014 at 11:41

Maroun

96.3k30 gold badges195 silver badges249 bronze badges

Collectives™ on Stack Overflow

adding arrayList to arraylist using loop

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related