Weighted Random

gistfile1.txt

static class Weighting {

	    String name;
	    int weight;

	    public Weighting(String name, int weight) {
	        this.name = name;
	        this.weight = weight;
	    }

	}

	public static String weightedRandom(List<Weighting> weightingOptions) {

	    int total = 0;
	    for (Weighting w : weightingOptions) {
	        total += w.weight;
	    }

	    int random = ThreadLocalRandom.current().nextInt(total);

	    int current = 0;
	    for (Weighting w : weightingOptions) {
	        current += w.weight;

	        if (random < current) {
	            return w.name;
	        }
	    }

	    return null;
	}

	@Test
	public void test() {

	    List<Weighting> weightings = new ArrayList<Weighting>();
	    weightings.add(new Weighting("Orange", 40));
	    weightings.add(new Weighting("Mango", 2));
	    weightings.add(new Weighting("Lemon", 2));
	    weightings.add(new Weighting("Apple", 1));
	    weightings.add(new Weighting("Banana", 1));

	    for (int i = 0; i < 100; i++) {
	        System.out.println(weightedRandom(weightings));
	    }
	}