java - Why does my list not change with lambda? -

this question has answer here:

• remove objects arraylist based on given criteria 6 answers

i have following simple method:

public void exercise2(list<string> list) {     list.stream().filter(s -> s.length() % 2 == 0).collect(collectors.tolist());   } 

and simple test, not complete successfully:

@test   public void testexercise2() {     lesson1 lesson1 = new lesson1();     list<string> list = new arraylist<>(arrays.aslist("alpha", "bravo", "charlie",                                                        "delta", "echo", "foxtrot"));     list<string> inputlist = new arraylist<>(list);     lesson1.exercise2(list);     assertequals("input " + inputlist.tostring(), arrays.aslist("echo"), list);   } 

streams never modify original list.

your function creates new list, ignores it.

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