java8 list交集差集并集
import java.util.ArrayList;
import java.util.List;
import java.util.stream.*;
import static java.util.stream.Collectors.toList;
public class test {
public static void main(String[] args) {
List<Student> list1 = new ArrayList<Student>();
Student st1 = new Student();
st1.setId("2");
st1.setName("");
st1.setAge("");
list1.add(st1);
Student sta = new Student();
sta.setId("1");
sta.setName("");
sta.setAge("");
list1.add(sta);
List<Student> list2 = new ArrayList<Student>();
Student st2 = new Student();
st2.setId("3");
st2.setName("");
st1.setAge("");
list2.add(st2);
// 差集 (list1 - list2)
List<Student> distinctByUniqueList = list1.stream()
.filter(item -> !list2.stream()
.map(e -> e.getId() )
.collect(Collectors.toList())
.contains(item.getId()))
.collect(Collectors.toList());
System.out.println("---差集 reduce1 (list1 - list2)---");
for(Student st : distinctByUniqueList){
System.out.println(st.getId());
System.out.println(st.getName());
}
// 交集
List<Student> intersection = list1.stream()
.filter(item -> list2.stream()
.map(e -> e.getId())
.collect(Collectors.toList())
.contains(item.getId()))
.collect(Collectors.toList());
System.out.println("---交集 intersection---");
for(Student st : intersection){
System.out.println(st.getId());
System.out.println(st.getName());
}
List<Student> add1 = distinctByUniqueList.parallelStream().collect(toList());
List<Student> add2 = intersection.parallelStream().collect(toList());
add1.addAll(add2);
System.out.println("---并集 listAll---");
for(Student st : add1){
System.out.println(st.getId());
System.out.println(st.getName());
}
}
}