使用Guava来计算笛卡尔积

比如我们要计算3个List的笛卡尔积，每个list的内容都是['a', 'b', 'c']， 请看下面的代码：

public class CartesianProductUtil {
 
    public static void main(String[] args) {
        ImmutableSet<Character> charList = ImmutableSet.of('a', 'b', 'c');
        Set<List<Character>> set = Sets.cartesianProduct(charList, charList, charList);
        for (List<Character> characters : set) {
            System.out.println(characters);
        }
    }
}

输出

[a, a, a]
[a, a, b]
[a, a, c]
[a, b, a]
[a, b, b]
[a, b, c]
[a, c, a]
[a, c, b]
[a, c, c]
[b, a, a]
[b, a, b]
[b, a, c]
[b, b, a]
[b, b, b]
[b, b, c]
[b, c, a]
[b, c, b]
[b, c, c]
[c, a, a]
[c, a, b]
[c, a, c]
[c, b, a]
[c, b, b]
[c, b, c]
[c, c, a]
[c, c, b]
[c, c, c]