使用笛卡尔积java对List进行排列组合
public class Test1 {@SuppressWarnings({ "rawtypes", "unchecked" })public static void main(String[] args) {ArrayList l1 = new ArrayList();l1.add(1);l1.add(2);l1.add(3);ArrayList l2 = new ArrayList();l2.add("a");l2.add("b");ArrayList l3 = new ArrayList();l3.add("+");l3.add("-");ArrayList ls = new ArrayList();ls.add(l1);ls.add(l2);ls.add(l3);List list = Dikaerji0(ls);System.out.println(list.size());for (Object object : list) {System.out.println(object);}}@SuppressWarnings({ "rawtypes", "unchecked" })public static ArrayList Dikaerji0(ArrayList al0) {ArrayList a0 = (ArrayList) al0.get(0);// l1ArrayList result = new ArrayList();// 组合的结果for (int i = 1; i < al0.size(); i++) {ArrayList a1 = (ArrayList) al0.get(i);ArrayList temp = new ArrayList();// 每次先计算两个集合的笛卡尔积，然后用其结果再与下一个计算for (int j = 0; j < a0.size(); j++) {for (int k = 0; k < a1.size(); k++) {ArrayList cut = new ArrayList();if (a0.get(j) instanceof ArrayList) {cut.addAll((ArrayList) a0.get(j));} else {cut.add(a0.get(j));}if (a1.get(k) instanceof ArrayList) {cut.addAll((ArrayList) a1.get(k));} else {cut.add(a1.get(k));}temp.add(cut);}}a0 = temp;if (i == al0.size() - 1) {result = temp;}}return result;}}?