java实现权重随机算法

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class WeightRandom {
static List<WeightCategory>  categorys = new ArrayList<WeightCategory>();
private static Random random = new Random();

public static void initData() {
WeightCategory wc1 = new WeightCategory("A",60);
WeightCategory wc2 = new WeightCategory("B",20);
WeightCategory wc3 = new WeightCategory("C",20);
categorys.add(wc1);
categorys.add(wc2);
categorys.add(wc3);
}

public static void main(String[] args) {
initData();
Integer weightSum = 0;
for (WeightCategory wc : categorys) {
weightSum += wc.getWeight();
}

if (weightSum <= 0) {
System.err.println("Error: weightSum=" + weightSum.toString());
return;
}
Integer n = random.nextInt(weightSum); // n in [0, weightSum)
Integer m = 0;
for (WeightCategory wc : categorys) {
if (m <= n && n < m + wc.getWeight()) {
System.out.println("This Random Category is "+wc.getCategory());
break;
}
m += wc.getWeight();
}

}

}

class WeightCategory {
private String category;
private Integer weight;

public WeightCategory() {
super();
}

public WeightCategory(String category, Integer weight) {
super();
this.setCategory(category);
this.setWeight(weight);
}

public Integer getWeight() {
return weight;
}

public void setWeight(Integer weight) {
this.weight = weight;
}

public String getCategory() {
return category;
}

public void setCategory(String category) {
this.category = category;
}
}