You can split asserting either a newline sequence \R on the left or right, or match a horizontal whitespace char \h using an alternation |

(?=\\R)|(?<=\\R)|\\h

Java demo

For example

String example = "Hello\nHow\nAre\nyou today? I Love Pizza"; //
String[] splited = example.split("(?=\\R)|(?<=\\R)|\\h");
for (String element : splited) {
    if (element.equals("\n")) element = "newline";
    System.out.println(element);
}

Output

Hello
newline
How
newline
Are
newline
you
today?
I
Love
Pizza

// Split on the following:
// look ahead for '\n' which is preceded by a character that is not '\n'
// OR look ahead for a character that is not '\n' preceded by '\n'
// OR a single space.
String regex = "(?=\\n)(?<!\\n)|(?!\\n)(?<=\\n)| ";

String example = "Hello\nHow\nAre\nyou today? I Love Pizza";

// This is the array that you want.
String[] splited = example.split(regex);

// This is just to display the contents of 'splited'.
int count = 0;
for (String part : splited) {
    count++;
    if (part.equals("\n")) {
        // Rather than print the actual newline, print its escape sequence
        System.out.printf("%2d. \\n%n", count);
    }
    else {
        System.out.printf("%2d. %s%n", count, part);
    }
}

Result:

 1. Hello
 2. \n
 3. How
 4. \n
 5. Are
 6. \n
 7. you
 8. today?
 9. I
10. Love
11. Pizza

You can do it simply by using lookbehind (specified by ?<=) or lookahead (specified by ?=) for \n and alternated with \s+ (for whitespace).

Demo:

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        String example = "Hello\nHow\nAre\nyou today? I Love Pizza"; //
        String[] splited = example.split("(?<=\\n)|(?=\\n)|\\s+");
        System.out.println(Arrays.toString(splited));
    }
}

Output:

[Hello, 
, How, 
, Are, 
, you, today?, I, Love, Pizza]