Hello.java

package tool;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
/**
*
* A simple Java Program to demonstrate how to use map and filter method Java 8.
* In this program, we'll convert a list of String into a list of Integer and
* then filter all even numbers.
*/
public class Hello {
  
 public static void main(String[] args) {
    List<String> numbers = Arrays.asList("1", "2", "3", "4", "5", "6");
    System.out.println("original list: " + numbers);
    List<Integer> even = numbers.stream()
                                .map(s -> Integer.valueOf(s))
                                .filter(number -> number % 2 == 0)
                                .collect(Collectors.toList());
  
    System.out.println("processed list, only even numbers: " + even);
   }
}


Output
original list: [1, 2, 3, 4, 5, 6]
the processed list, only even numbers: [2, 4, 6]