有什么方法可以使用Lambda Stream根据集合过滤流或列表中的集合字段?
例:
List<Person> persons = new ArrayList<Person>();
Set<String> hobbySet1 = new HashSet<String>();
hobbySet1.add("H1");
hobbySet1.add("H2");
hobbySet1.add("H3");
Set<String> hobbySet2 = new HashSet<String>();
hobbySet2.add("H2");
hobbySet2.add("H4");
Set<String> hobbySet3 = new HashSet<String>();
hobbySet3.add("H3");
Set<String> hobbySet4 = new HashSet<String>();
hobbySet4.add("H4");
persons.add(new Person("P1", hobbySet1));
persons.add(new Person("P2", hobbySet2));
persons.add(new Person("P3", hobbySet3));
persons.add(new Person("P4", hobbySet4));
Set<String> searchHobby = new HashSet<String>();
searchHobby.add("H1");
searchHobby.add("H3");
我想根据searchHobby从“列表”人员中过滤出兴趣爱好,以便只保留在searchHobby中指定了兴趣爱好的那些人。
我知道如何使用简单的for循环来实现这一目标。
List<Person> result = new ArrayList<Person>();
for (String sHobby : searchHobby) {
for (Person p : persons) {
Set<String> pHobbySet = p.getHobbies();
for (String pHobby : pHobbySet) {
if (pHobby.equalsIgnoreCase(sHobby)) {
Optional<Person> wasAdded = result.stream().filter(s->s.getName()==p.getName()).findAny();
if(wasAdded.isEmpty()) {
result.add(p);
break;
}
}
}
}
}
我正在寻找Java流过滤器解决方案。
附言人
public class Person {
String name;
Set<String> hobbies;
public Person(String name, Set<String> hobbies) {
this.name = name;
this.hobbies = hobbies;
}
public String getName(){
return name;
}
public Set<String> getHobbies(){
return hobbies;
}
}
最佳答案
如果某些爱好匹配,anyMatch将返回true。
List<Person> personsWithHobby = persons.stream()
.filter(person -> person.getHobbies().stream()
.anyMatch(searchHobby::contains))
.collect(Collectors.toList());