Post a Comment On: j4neiros

I found this interesting problem here: 
https://javarevisited.blogspot.com/2014/11/how-to-find-missing-number-on-integer-array-java.html
but I think the solution is too long, see mine below:

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class MissingIntegers {

    public static void main(String[] args) {
       
        Set<Integer> s1 = new HashSet<>(Arrays.asList(new Integer[]{1, 2, 3, 4, 9, 8}));
        Set<Integer> s2 = new HashSet<>(IntStream.rangeClosed(1, 10).boxed().collect(Collectors.toList()));

        s2.removeAll(s1);
        System.out.println(s2);
    }
   
}

In fact we don't need the intermediate List in the case of Set 2, we can use the toCollection method of Collectors:

Set<Integer> s2 = IntStream.rangeClosed(1, 10).boxed().collect(Collectors.toCollection(HashSet::new));

Next day I came up with another solution:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class MissingIntegers {

    public static void main(String[] args) {
       
        List<Integer> L1 = Arrays.asList(new Integer[]{1, 2, 3, 4, 9, 2, 8});
        List<Integer> L2 = IntStream.rangeClosed(1, 10).boxed().collect(Collectors.toCollection(ArrayList::new));
       
        L2.removeAll(L1);
        System.out.println(L2);
    }
   
}