WeightedCollection.java

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package com.runehive.game.world.entity.mob.npc.drop;
 
import java.util.NavigableMap;
import java.util.Random;
import java.util.TreeMap;
 
public class WeightedCollection<E> {
    private final NavigableMap<Double, E> map = new TreeMap<>();
    private final Random random;
    private double total = 0;
 
    public double getTotal() {
        return total;
    }
 
    public WeightedCollection() {
        this(new Random());
    }
 
    public WeightedCollection(Random random) {
        this.random = random;
    }
 
    public WeightedCollection<E> add(double weight, E result) {
        if (weight <= 0) return this;
        total += weight;
        map.put(total, result);
        return this;
    }
 
    public E next() {
        double value = random.nextDouble() * total;
        return map.higherEntry(value).getValue();
    }
}