[MATH-942] DiscreteDistribution.sample(int) may throw an exception if first element of singletons of sub-class type

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.2
• Assignee: Unassigned
• Reporter: Piotr Wydrych
• Created: 09/Mar/13 15:05
• Updated: 07/Apr/13 09:20
• Resolved: 10/Mar/13 12:02

Description

Creating an array with Array.newInstance(singletons.get(0).getClass(), sampleSize) in DiscreteDistribution.sample(int) is risky. An exception will be thrown if:

• singleons.get(0) is of type T1, an sub-class of T, and
• DiscreteDistribution.sample() returns an object which is of type T, but not of type T1.

To reproduce:

List<Pair<Object,Double>> list = new ArrayList<Pair<Object, Double>>();
list.add(new Pair<Object, Double>(new Object() {}, new Double(0)));
list.add(new Pair<Object, Double>(new Object() {}, new Double(1)));
new DiscreteDistribution<Object>(list).sample(1);

Attaching a patch.