Java Stream - 如何使用有状态的lambda表达式

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;


public class Main {
    public static void main(String[] args) {
      Integer[] intArray = {1, 2, 3, 4, 5, 6, 7, 8 };
      List<Integer> listOfIntegers = new ArrayList<>(Arrays.asList(intArray));

      List<Integer> serialStorage = new ArrayList<>();
      
      System.out.println("Serial stream:");
      listOfIntegers
          .stream()
          
          // Don't do this! It uses a stateful lambda expression. 
          .map(e -> { serialStorage.add(e); return e; })
          
          .forEachOrdered(e -> System.out.print(e + " "));
      System.out.println("");
   
      serialStorage
          .stream()
          .forEachOrdered(e -> System.out.print(e + " "));
      System.out.println("");

      System.out.println("Parallel stream:");
      List<Integer> parallelStorage = Collections.synchronizedList(
          new ArrayList<>());
      listOfIntegers
          .parallelStream()
          
          // Don't do this! It uses a stateful lambda expression.
          .map(e -> { parallelStorage.add(e); return e; })
          
          .forEachOrdered(e -> System.out.print(e + " "));
      System.out.println("");
   
      parallelStorage
          .stream()
          .forEachOrdered(e -> System.out.print(e + " "));
      System.out.println("");

    }
}

/*
 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */