hey, I am stuck with this : how to convert arrayList to int[] ?
got this so far
ArrayList array;
here i add objects to array;
int [] tab = new int[array.size()];
then I use :
array.toArray(tab);
but it simply does not work, can anybody help me out ?
cheers, Lukasz
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class XXXX
{
public static void main(String[] args)
{
List<Integer> list = new ArrayList<Integer>();
// ArrayList only contains objects, can't hold int
list.add(1); // use autoboxing to add an Integer
list.add(2);
Integer[] ar = list.toArray(new Integer[list.size()]);
// create an int array from an Integer array
int[] intArray = new int[ar.length];
for(int i =0; i<ar.length; ++i)
{
intArray[i] = ar[i];
}
System.out.println(Arrays.toString(intArray));
}
}
>
So what is the intention of method Object[] toArray(), if it is not using reflection and by using this method I cant explicitly cast to my class and I am loosing the information about my destination class, and why method Object[] toArray(Object[]) allows it. It is the question to the author of this method, still I cant buy this method toArray(). Please help!
If there is a reasonable intention about this method, should it be included in JavaDoc.
Message was edited by:
dom
> Sorry, in Java 1.4 you have to make an explicit cast,
> so it's
>
> int [] tab = (int[]) array.toArray(new int[0]);
This doesn't work because List's can only hold Objects, and the toArray() method can only work with an Object[], but not an array of primitives.
The only way to do it is the old fashioned way, loop thru the list and populate the array.
~Tim
> This doesn't work because List's can only hold
> Objects, and the toArray() method can only work with
> an Object[], but not an array of primitives.
>
> The only way to do it is the old fashioned way, loop
> thru the list and populate the array.
>
> ~Tim
Like this, ChuckBing had the right Idea, but too much code
public static void main(String[] args) {
List<Integer> array = new ArrayList<Integer>();
array.add(1);
array.add(2);
array.add(3);
int[] tab = new int[array.size()];
for(int i = 0; i<array.size(); i++)
{
tab[i] = array.get(i);
}
System.out.println(Arrays.toString(tab));
}
~Tim>