JAVA中两个列表的交集[重复]

Question

我正在尝试在 JAVA 中获取两个列表之间的交集，请在下面找到列表

列表 1：

List<EligViewEventSubject> list1=  new ArrayList<>();

list1=   [EligViewEventSubject [event=EOD, subjectTypeCd=HOLDINGS, region=IA], EligViewEventSubject [event=EOD, subjectTypeCd=ASSETS, region=IA]]

清单 2：

List<EligViewEventSubject> list2=  new ArrayList<>();

list2 = [EligViewEventSubject [event=EOD, subjectTypeCd=ASSETS, region=IA]]

上面的结果应该如下所示

List<EligViewEventSubject> resultList =  new ArrayList<>();

resultList = [EligViewEventSubject [event=EOD, subjectTypeCd=ASSETS, region=IA]]

简而言之，我只想要匹配的（交叉点）

我已经尝试过以下方法：

List<EligViewEventSubject> unionList = new ArrayList<>(list1);
        unionList.addAll(list2);

List<EligViewEventSubject> intersectionList = new ArrayList<>(list1);
        intersectionList.retainAll(list2);

我得到的联合列表：

[EligViewEventSubject [event=EOD, subjectTypeCd=HOLDINGS, region=IA], EligViewEventSubject [event=EOD, subjectTypeCd=ASSETS, region=IA], EligViewEventSubject [event=EOD, subjectTypeCd=ASSETS, region=IA]]

交点是[]

请分享您对此的看法。

Answer 1

请参考这个问题，因为这已经被回答了。 Intersection and union of ArrayLists in Java

总而言之，你可以在java中得到两个数组列表的交集：

public <T> List<T> intersection(List<T> list1, List<T> list2) {
    List<T> list = new ArrayList<T>(); 

    for (T t : list1){
       if(list2.contains(t)){
           list.add(t); 
       } 
    } 

   return list; 
}