Imagine that you have this situation:
List<String> al = new ArrayList<>(); al.add("[I] am"); al.add("you are"); al.add("I"); al.add("[I] like java");
Now I want to count the sequence [I] (in this case it will count 2 times). The Link How to count the number of occurrences of an element in a List just pust one word, but on my example I have more than one, i.e, Collections.frequency(al, “[I]”) do not work.
How can I achieve this preferentially using Java 8 ?
Another way is to split the stream by space and then check whether chunk is equal to
System.out.println(al.stream().map((w) -> w.split(" ")).flatMap(Arrays::stream).filter((i) ->i.equals("[I]")).count());
equals have advantage over contains because let say your list contains words like below
List<String> al = new ArrayList<>(); al.add("[I] am [I]"); al.add("you are"); al.add("I"); al.add("[I] like java");
This solution will return 3 as expected but the solution mentioned by Bohuslav Burghardt will return 2