Java Stream - 如何将String数组减少为单个String值

import java.util.function.BinaryOperator;
import java.util.stream.Stream;

public class Main {

  public static void main(String[] args) {
    BinaryOperator<String> adder = (a, b) -> {
      return a + b;
    };
    String[] alphabets = { "Just", " Java 8"," HTML" };
    String sum = Stream.of(alphabets).reduce(" ", adder);

    System.out.println("Alphabets:" + sum);
  }

}