java - JAVA中两个列表的交集

Question

我正在尝试获取JAVA中两个列表之间的交集，请找到下面的列表

列表 1:

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

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

列表 2:

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

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

上述结果应如下所示

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

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

简而言之，我想要单独的匹配项(交叉点)

我尝试过以下方法:

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

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

我得到的联盟列表为:

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

交集是[]

请分享您对此的想法。

Answer 1

请引用此问题，因为该问题已经得到解答。 Intersection and union of ArrayLists in Java

总而言之，您可以在 java 中获取两个数组列表的交集，如下所示:

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; 
}