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How to count element after filtering in Java?
Let’s say the following is the String List:
List<String> list = new ArrayList<>(); list.add("Tom"); list.add("John"); list.add("David"); list.add("Paul"); list.add("Gayle"); list.add("Narine"); list.add("Joseph");
Now, let’s say you need to filter elements beginning with a specific letter. For that, use filter() and startsWith():
long res = list .stream() .filter((s) -> s.startsWith("J")) .count();
We have also counted the elements above after filtering using count().
The following is an example to count element after filtering in Java:
Example
import java.util.ArrayList; import java.util.List; public class Demo { public static void main(final String[] args) { List<String> list = new ArrayList<>(); list.add("Tom"); list.add("John"); list.add("David"); list.add("Paul"); list.add("Gayle"); list.add("Narine"); list.add("Joseph"); long res = list .stream() .filter((s) -> s.startsWith("J")) .count(); System.out.println("How many strings begin with letter J? = "+res); } }
Output
How many strings begin with letter J? = 2
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