RFC: draft API for JEP 269 Convenience Collection Factories (original) (raw)

Paul Sandoz paul.sandoz at oracle.com
Thu Oct 15 14:40:18 UTC 2015

On 15 Oct 2015, at 16:28, Stephen Colebourne <scolebourne at joda.org> wrote:

I've been working on a Java 8 wrapper class around double[] in my day job, and added the following factory method: /** * Obtains an instance with entries filled using a function. *

* The function is passed the array index and returns the value for that index. * * @param size the number of elements * @param valueFunction the function used to populate the value * @return an array initialized using the function */ public static DoubleMatrix1D of(int size, IntToDoubleFunction valueFunction) { if (size == 0) { return EMPTY; } double[] array = new double[size]; for (int i = 0; i < array.length; i++) { array[i] = valueFunction.applyAsDouble(i); } return new DoubleMatrix1D(array); }

Within that method you can use Arrays.setAll(array, valueFunction). In hindsight it would have been useful for that method to return the filled array.

Paul.

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