What is the difference between ArrayList al = new ArrayList(); and ArrayList al = new ArrayList(0)?
3 Answers
ArrayList(0)
Empty list with the specified initial capacity. Hense none for 0
ArrayList()
Empty list with an initial capacity of ten.
Please read the following: http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html
Comments
If you look on the API, it says, ArrayList() - Constructs an empty list with an initial capacity of ten.
ArrayList(int initialCapacity) - Constructs an empty list with the specified initial capacity.
answered Jan 12, 2011 at 6:48
Abimaran Kugathasan
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1 Comment
Lovis
in (open) JDK8, this seems to be not the case. It does say that it creates an initial capacity of 10, but in fact it creates a capacity of 0: grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/…
new ArrayList() gives you an array list with default initial capacity (how much memory is initially allocated from the ArrayList). new ArrayList(0) gives you an array list with zero initial capacity. As soon as an element is added to the list, capacity is allocated.
new ArrayList()is equivalent to (and probably implemented in terms of)new ArrayList(10)