java8 stream test

import java.util.*;
import java.util.stream.*;

class Main {
    public static void main(String[] args) {
        List<Integer> list = Arrays.asList(-1,0,1,2,3);
        System.out.println(list);
        System.out.println(list.stream().filter(i->i>0).collect(Collectors.toList()));
        System.out.println(list.stream().filter(i->i>0).collect(Collectors.toList()).add(1));
        System.out.println(list);
        
        List<Integer> a = list.stream().filter(i->i>0).collect(Collectors.toList());
        a.add(1);
        System.out.println(a);
        System.out.println(list);
    }
}