Re: How to do Arrays.asList on only part of an Object[] array?
laredotornado wrote:
On Nov 4, 4:25 pm, Tom Anderson <t...@urchin.earth.li> wrote:
On Wed, 4 Nov 2009, laredotornado wrote:
As you may know, the Arrays.asList method will return an ArrayList
object from an Object[] array. What is the easiest way to achieve this
when you only want a specific range of that Object[] array, say, its
first element up until it's length - 1 element?
Arrays.asList(anArray).subList(startIndex, endIndex);
Both the array list and the sub-list are lightweight wrappers, so there's
no copying, just two method calls and some arithmetic on each access.
Forgot to update this thread, but since there was consensus on Tom's
solution I tried it out and it worked great. 5 stars, - Dave
Just note that as Tom wrote then asList and subList does not copy
data.
Besides meaning good performance it also means that modifications
to the list also affects the array.
import java.util.Arrays;
import java.util.List;
public class Backing {
public static void main(String[] args) {
String[] sa = { "A", "BB", "CCC", "DDDD" };
List<String> sl = Arrays.asList(sa).subList(1, 3);
sl.set(0, "BBX");
sl.set(1, "CCCX");
for(String s : sa) {
System.out.println(s);
}
}
}
outputs:
A
BBX
CCCX
DDDD
That is fine.
You just need to be aware of it.
Arne
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