ContainsAll List Java

Question

     List a = new ArrayList();
     List b = new ArrayList();

     a.add(\"apple\");
     a.add(\"orange\");         


        

Answer 1

Because B is empty. A contains everything in B.

Answer 2

Obviously a typo. b.add("orange") is what was meant.

Answer 3

List.ContainsAll will return true if the list contains all of the elements within the target. Because B is empty A contains all the same elements as B.

Answer 4

It's a matter of logic: does A contain all the elements inside B?

This can be seen as for each element in B, does this element belong to A too?

You can understand that the condition is true, since B is empty, there is no element to check: for each element in B, so for no element.

Answer 5

Because b is empty. Therefore there is nothing in b that is not in a.