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

class Test {
    public static void main(String[] args) {
        List<Integer> data = Collections.synchronizedList(new ArrayList<>());
        Arrays.asList(1,2,3,4,5,6).parallelStream()
                .map(i -> {data.add(i); return i;}) // AVOID STATEFUL LAMBDA EXPRESSIONS!
                .forEachOrdered(i -> System.out.print(i+" "));
        System.out.println();
        for(Integer e: data) {
            System.out.print(e+" ");
        }
    }
}