Converting a Double Array list to a double array

Question

I am wanting to convert my double ArrayList to a double array but I am unsure how. Here is my current code listing :

ArrayList<Double> aL= new ArrayList<Double>();  
double x[] = new double[aL.size()];
aL.add(10.0);  
aL.add(5.0);  
aL.add(2.0);
for(int i =0; i < x.length; i++){
//some code
}

But then I am not sure where to go and I am unable to find something on the internet/ in books to give me any insight. Thanks.

This question shows no effort. Please try consulting the [documentation for List](http://docs.oracle.com/javase/7/docs/api/java/util/List.html). — jahroy, Mar 21 '13 at 18:33
It's pretty straightforward; you've got everything you need in your code (except the contents of the loop). What problems are you having? — Reinstate Monica -- notmaynard, Mar 21 '13 at 18:39
Helpful links: http://docs.oracle.com/javase/6/docs/api/java/util/ArrayList.html http://docs.oracle.com/javase/6/docs/api/java/lang/Double.html http://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html — Reinstate Monica -- notmaynard, Mar 21 '13 at 18:41
Here's [one duplicate](http://stackoverflow.com/q/6018267/778118)... and [another](http://stackoverflow.com/q/6147421/778118)... and [another](http://stackoverflow.com/q/960431/778118)... It's a shame that anybody would bother to answer a question like this. It should be downvoated and closed. — jahroy, Mar 21 '13 at 19:04

score -2 · Answer 1 · answered Mar 21 '13 at 18:32

-2

You can use Collection API to convert list to array. Try uL.toArray();

answered Mar 21 '13 at 18:32

Sudhanshu Umalkar

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Nope. That will not work. See Gourabp's comment above. – michaelsnowden Dec 07 '13 at 21:44

Gilbert Le Blanc · Accepted Answer · 2013-03-21T18:44:38.413

-4

First, you need to create your ArrayList. Then you need to create your array.

List<Double> aL= new ArrayList<Double>();  
aL.add(10.0D);  
aL.add(5.0D);  
aL.add(2.0D);

double x[] = new double[aL.size()];
for(int i = 0; i < x.length; i++){
     x[i] = al.get(i);
}

You can use an ArrayList method to copy the ArrayList to an array.

List<Double> aL= new ArrayList<Double>();  
aL.add(10.0D);  
aL.add(5.0D);  
aL.add(2.0D);

double x[] = aL.toArray();

edited Mar 21 '13 at 18:44

answered Mar 21 '13 at 18:38

Gilbert Le Blanc

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This is not going to work you will get a compile time :Type mismatch: cannot convert from Object[] to double[] – GKP Oct 11 '13 at 21:47

Converting a Double Array list to a double array

2 Answers2