對物件集合進行處理時，整天for迴圈篩選，感覺跟不上時代。搜了搜，學了學java8的Stream，並用來替代for迴圈篩選。

public class StreamTest {

    public static void main (String[] args) {
        List<Person> persons = Arrays.asList(
                new Person("e1", "l1"),
                new Person("e2", "l1"),
                new Person("e3", "l2"),
                new Person("e4", "l2"),
                new Person("e5", "l3"),
                new Person("e6", "l3"),
                new Person("e7", "l3")

        );
        //.filter（過濾條件）
        //.collect(Collectors.toList()) 把結果蒐集到List之中。
        persons = persons.stream().filter(person -> person.getLastName().equals("l3")).collect(Collectors.toList());
        persons.forEach(person -> {
            System.out.println(person.getName());
        });


    }
}
 

public class Person {


    private String name;
    private String lastName;

    public Person(String name, String lastName) {
        this.name = name;
        this.lastName = lastName;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}
 

e5
e6
e7