Java Stream How to - Filter Person List and map to name, then collect to create string

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Question

We would like to know how to filter Person List and map to name, then collect to create string.

Answer

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
//from   ww w .  ja  v a  2 s  .  co  m
public class Main {

  public static void main(String[] args) throws Exception {
    List<Person> persons =
        Arrays.asList(
            new Person("Max", 18),
            new Person("Peter", 23),
            new Person("Pamela", 23),
            new Person("David", 12));   
    

    String names = persons
        .stream()
        .filter(p -> p.age >= 18)
        .map(p -> p.name)
        .collect(Collectors.joining(" and ", "In Germany ", " are of legal age."));

    System.out.println(names);
  }

}
class Person {
  String name;
  int age;

  Person(String name, int age) {
      this.name = name;
      this.age = age;
  }

  @Override
  public String toString() {
      return name;
  }
}

The code above generates the following result.

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