Java 实现超简单么。。 都不用自己写算法实现

```
/**
* 从 有值的 list 里取交集
* @param lists
* @return
*/
public List<Object> intersection(List<List<Object>> lists) {
if(lists == null || lists.size() == 0){
return null;
}
ArrayList<List<Object>> arrayList = new ArrayList<>(lists);
for (int i = 0; i < arrayList.size(); i++) {
List<Object> list = arrayList.get(i);
// 去除空集合
if (list == null || list.size() == 0) {
arrayList.remove(list);
i-- ;
}
}
if(arrayList.size() == 0){
return null;
}
List<Object> intersection = arrayList.get(0) ;
// 就只有一个非空集合，结果就是他咯
if(arrayList.size() == 1){
return intersection;
}
// 有多个非空集合，直接挨个交集
for (int i = 1; i < arrayList.size()-1; i++) {
intersection.retainAll(arrayList.get(i));
}
return intersection;
}



public void test() {
List<Object> list1 = new ArrayList<Object>();
List<Object> list2 = new ArrayList<Object>();
List<Object> list3 = new ArrayList<Object>();
List<Object> list4 = new ArrayList<Object>();
List<Object> list5 = new ArrayList<Object>();

initList(list1);
initList(list2);
initList(list3, "3", "4", "5");
initList(list4, "3","4");
initList(list5, "8","3", "3","4");

System.out.println(intersection(Arrays.asList(list1,list2,list3,list4,list5)));

}


/**
* 给 List 添加元素
*
* @param list
* @param item
*/
public void initList(List<Object> list, Object... item) {
if (list == null) {
throw new IllegalArgumentException("list can't be empty!");
}
if (item == null || item.length == 0) {
return;
}
list.addAll(Arrays.asList(item));
}

public static void main(String[] args) {
new Test().test();
}

```