Zunda's 1-digit addition problem Java 11

tbpgr's "Zunda 1-digit addition problem Ruby edition" has been implemented in Java 11 released in September 2018.

import java.util.stream.IntStream;

public class Main {
    public static void main(String[] args) {    
        IntStream.range(1, 10)
            .boxed()
            .flatMap(x -> {
                return IntStream.range(1, 10).mapToObj(y -> {
                    int z = x + y;
                    var tilda = "~".repeat(z);
                    return String.format("%d+%d=%s%d", x, y, tilda, z);
                });
            })
            .forEach(System.out::println);
    }
}

The Java 11-like point of this code is that it uses String :: repeat introduced from Java 11. The API that "generates a string that repeats a certain string n times" is not provided as a standard in Java, so I had to create a Util method or prepare an external library by myself. , String :: repeat is implemented in the standard library from Java 11 (Reference: https://qiita.com/neko_the_shadow/items/78ad73e86f45e4994a89)

The execution result was as follows (´ ・ ω ・ ｀)

1+1=~~2
1+2=~~~3
1+3=~~~~4
1+4=~~~~~5
1+5=~~~~~~6
1+6=~~~~~~~7
1+7=~~~~~~~~8
1+8=~~~~~~~~~9
1+9=~~~~~~~~~~10
2+1=~~~3
2+2=~~~~4
2+3=~~~~~5
2+4=~~~~~~6
2+5=~~~~~~~7
2+6=~~~~~~~~8
2+7=~~~~~~~~~9
2+8=~~~~~~~~~~10
2+9=~~~~~~~~~~~11
3+1=~~~~4
3+2=~~~~~5
3+3=~~~~~~6
3+4=~~~~~~~7
3+5=~~~~~~~~8
3+6=~~~~~~~~~9
3+7=~~~~~~~~~~10
3+8=~~~~~~~~~~~11
3+9=~~~~~~~~~~~~12
4+1=~~~~~5
4+2=~~~~~~6
4+3=~~~~~~~7
4+4=~~~~~~~~8
4+5=~~~~~~~~~9
4+6=~~~~~~~~~~10
4+7=~~~~~~~~~~~11
4+8=~~~~~~~~~~~~12
4+9=~~~~~~~~~~~~~13
5+1=~~~~~~6
5+2=~~~~~~~7
5+3=~~~~~~~~8
5+4=~~~~~~~~~9
5+5=~~~~~~~~~~10
5+6=~~~~~~~~~~~11
5+7=~~~~~~~~~~~~12
5+8=~~~~~~~~~~~~~13
5+9=~~~~~~~~~~~~~~14
6+1=~~~~~~~7
6+2=~~~~~~~~8
6+3=~~~~~~~~~9
6+4=~~~~~~~~~~10
6+5=~~~~~~~~~~~11
6+6=~~~~~~~~~~~~12
6+7=~~~~~~~~~~~~~13
6+8=~~~~~~~~~~~~~~14
6+9=~~~~~~~~~~~~~~~15
7+1=~~~~~~~~8
7+2=~~~~~~~~~9
7+3=~~~~~~~~~~10
7+4=~~~~~~~~~~~11
7+5=~~~~~~~~~~~~12
7+6=~~~~~~~~~~~~~13
7+7=~~~~~~~~~~~~~~14
7+8=~~~~~~~~~~~~~~~15
7+9=~~~~~~~~~~~~~~~~16
8+1=~~~~~~~~~9
8+2=~~~~~~~~~~10
8+3=~~~~~~~~~~~11
8+4=~~~~~~~~~~~~12
8+5=~~~~~~~~~~~~~13
8+6=~~~~~~~~~~~~~~14
8+7=~~~~~~~~~~~~~~~15
8+8=~~~~~~~~~~~~~~~~16
8+9=~~~~~~~~~~~~~~~~~17
9+1=~~~~~~~~~~10
9+2=~~~~~~~~~~~11
9+3=~~~~~~~~~~~~12
9+4=~~~~~~~~~~~~~13
9+5=~~~~~~~~~~~~~~14
9+6=~~~~~~~~~~~~~~~15
9+7=~~~~~~~~~~~~~~~~16
9+8=~~~~~~~~~~~~~~~~~17
9+9=~~~~~~~~~~~~~~~~~~18