Bonemeal util & weighted list

src/main/java/ru/bclib/util/WeightedList.java

@@ -0,0 +1,34 @@
+package ru.bclib.util;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+public class WeightedList<T> {
+	private final List<Float> weights = new ArrayList<Float>();
+	private final List<T> values = new ArrayList<T>();
+	private float maxWeight;
+	
+	public void add(T value, float weight) {
+		maxWeight += weight;
+		weights.add(maxWeight);
+		values.add(value);
+	}
+	
+	public T get(Random random) {
+		if (maxWeight < 1) {
+			return null;
+		}
+		float weight = random.nextFloat() * maxWeight;
+		for (int i = 0; i < weights.size(); i++) {
+			if (weight <= weights.get(i)) {
+				return values.get(i);
+			}
+		}
+		return null;
+	}
+
+	public boolean isEmpty() {
+		return maxWeight == 0;
+	}
+}