turning a null string into a white space in a morse code reader

I am trying to write a morse code translator for a challenge. at the moment I have got as far as translating the morse code into a String array and am passing it through a for loop to build the message.

I am currently getting HEYnullnullJUDE and am working out how to detect 2 spaces which in morse code will act as a word space. however when I use an if statement to detect .isEmpty or .isBlank or .length() == 0 the for loop exits and I get a return of:

9
this is split  = [...., ., -.--, , , .---, ..-, -.., .]
H
H
E
HE
Y
HEY

for some reason once it hits Null, instead of executing the nullCount it just exits and return HEY and I'm not sure.

what is the best way of turning HEYnullnullJUDE which i am getting now into HEY JUDE and detecting the double space in the morse code?

this is taken from this codewars challenge: https://www.codewars.com/kata/54b724efac3d5402db00065e/train/java

import java.util.Arrays;
public class MorseCodeDecoder {
    public static String decode(String morseCode) {
        
       String[] split = morseCode.trim().split(" ");
        int length = split.length;
        System.out.println(length);
        System.out.println("this is split  = " + Arrays.toString(split));

        MorseCode morseCoder = new MorseCode();
        
        String message = "";

        for (int i =0; i < length; i++){
          int nullCount = 0;
            

// this is where the code exits for some reason

            if(morseCoder.get(split[i]) == null{
              nullCount++;
              System.out.println(nullCount);
              if (nullCount == 2){
                nullCount =0;
                message = message + " ";
              }
            }
// if this is "if"statment is removed i get HEYnullnullJUDE

          System.out.println (morseCoder.get(split[i]));
        message = message + morseCoder.get(split[i]);
            System.out.println(message);
              
        }
      return message;
      
    }
}

samble test
import org.junit.Test;
import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.assertThat;

public class MorseCodeDecoderTest {
    @Test
    public void testExampleFromDescription() {
      assertThat(MorseCodeDecoder.decode(".... . -.--   .--- ..- -.. ."), is("HEY JUDE"));
    }
}

Your input is ".... . -.-- .--- ..- -.. .".

Since you call trim(), there will be no leading or trailing spaces seen by split().

To see the 3 spaces as a single space in the result of the split(), you basically don't want to split on the middle of the 3 spaces. Said another way, you only want to split on a space that follows a non-space or a space that is followed by a non-space.

        Split on these
    ↓ ↓    ↓ ↓    ↓   ↓   ↓
.... . -.--   .--- ..- -.. .
            ↑
      Don't split on this

If you use split("(?<=[^ ]) | (?=[^ ])"), then the result becomes:

{ "....", ".", "-.--", " ", ".---", "..-", "-..", "." }

Here the space in the morse code truly becomes a string with a single space.

I'll leave the rest to you, e.g. how to make morseCoder.get(" ") return a " " (or ' ', whatever the type may be).

UPDATE

From comment:

> MorseCode.get does not include " " space detection

morseCoder.get(" ") return a " " was just an example of how it could be solved. Alternatively, simply check if a space is encountered, before calling morseCoder.get(...), e.g.

StringBuilder buf = new StringBuider();
for (String symbol : split) {
    if (symbol.equals(" ")) {
        buf.append(' ');
    } else {
        String str = morseCoder.get(split[i]);
        buf.append(str == null ? "�" : str);
    }
}
String message = buf.toString();