Collectors.reducing for joining Strings

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class CollectorReduceFlight {
public static void main(String[] dataBag) {

List<Person> persons = Arrays.asList(
new Person("raj"),
new Person("rose"),
new Person("jack")
);

String names = persons
.stream()
.map(Person::getName)
.collect(Collectors.reducing((s1, s2) ->s1+s2))
.get();
System.out.println("1) Names: "+ names);

String temps = persons.stream()
.collect( Collectors.reducing( 
"2) Names: ",
Person::getName, 
(s1, s2) -> s1 + s2 ));

System.out.println(temps);

}
}
Output:
Names: rajrosejack

Names: rajrosejack

Explanation:
Collectors.reducing((s1, s2) ->s1+s2): 
Takes name of each person object in String stream  and then reducing the resulting string stream using a String accumulator and the appends to it the name of each person.
If the stream is empty then it will throw an Exception. NoSuchElementException.

Collectors.reducing("2) Names: ", Person::getName,  (s1, s2) -> s1 + s2 )):
This starts the reduction process with the string "2) Names: ".
If the stream is empty then it will return only "2) Names: ".

In this example it takes the each person name and join all the names with prepended string as "2) Names:"