Array not printing on morse code program

Question

I am very new to java and have been having trouble with my morse code program. Please bear with me, but when entering text to be translated from morse code to english it just prints null in place of letters. Any help would be greatly appreciated.

import java.util.Scanner;

public class MorseCode
{
    public static void main(String[] args)
    {
        Scanner Input = new Scanner(System.in);

        System.out.println("To convert English to Morse Code, type M. To convert Morse Code to English, type E.");

        String cType = Input.nextLine();

        String type = cType.toLowerCase();

        if("m".equals(type))
        {
            String eng;
            System.out.println("Please enter the English text to be translated.");
            eng = Input.nextLine();
            EToM(eng);
        }
        else
        {
            String morse;
            System.out.println("Please enter the Morse code text to be translated, with multiple words seperated by a |.");
            morse = Input.nextLine();
            MToE(morse);
        }
    }
    public static void EToM(String eng)
    {
        String EToMList[] = {".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".--", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--..", ".----", "..---", "...--", "....-", ".....", "-....", "--...", "----.", "-----", "|"};
        String alphabet = "abcdefghijklmnopqrstuvwxyz123456789 ";
        String translation[] = new String[eng.length()];

        for(int x = 0; x < eng.length(); x++)
        {
            for(int y = 0; y < alphabet.length(); y++)
            {
                if(eng.charAt(x) == alphabet.charAt(y))
                {
                    translation[x] = EToMList[y];
                }
            }
        }

        System.out.println("Your translated message is:");

        for(int z = 0; z < eng.length(); z++)
        {
            System.out.println(translation[z]); 
        }
    }

    public static void MToE(String morse)
    {
        int arraySize = 0;
        String MToEList[] = {".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".--", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--..", ".----", "..---", "...--", "....-", ".....", "-....", "--...", "----.", "-----", "|"};
        String alphabet = "abcdefghijklmnopqrstuvwxyz123456789 ";
        char space = '|';

        for(int x = 0; x < morse.length(); x++)
        {
            if(morse.charAt(x) == space)
            {
                arraySize += 1;
            }
        }

        String segmentedMessage[] = new String[arraySize];
        String translation[] = new String[arraySize];

        int a = 1;
        int counter = 0;

        for(int y = 0; y < morse.length(); y++)
        {
            if(morse.charAt(y) == space)
            {
                segmentedMessage[counter] = morse.substring((a - 1), (y + 1));
                a = y;
            }
        }

        for(int z = 0; z < segmentedMessage.length; z++)
        {
            for(int i = 0; i < alphabet.length(); i++)
            {
                if(segmentedMessage[z] == MToEList[i])
                {
                    translation[z] = alphabet.substring(i - 1, i + 1);
                }
            }
        }

        System.out.println("Your translated message is:");

        for(int j = 0; j < translation.length; j++)
        {
            System.out.println(translation[j]);
        }
    }
}       

Answer 1

I think your problem lies at the line

if(segmentedMessage[z] == MToEList[i])

See earlier you were comparing char types, char is a primitive type meaning you can use == to safely compare values. On the line I mentioned you are comparing String types. String is a java Object.

All Java objects should use .compare instead of ==

Example

char char1 = 'c';
char char2 = 'c';
char1 == char2 // true!

String str1 = "c";
String str2 = "c";
str1 == str2 // not always going to be true, even tho it would seem that way
str1.equals(str2) // true!

Answer 2

The first problem that I see is that in your MToE method, in this section:

int a = 1;
int counter = 0

for(int y = 0; y < morse.length(); y++)
{
    if(morse.charAt(y) == space)
    {
        segmentedMessage[counter] = morse.substring((a - 1), (y + 1));
        a = y;
    }
}

You never increment counter, and so only the first element of segmentedMessage will ever be filled with a morse string. If you're getting one character and then a bunch of nulls, this is probably your issue.

Further, in this line in the same method:

translation[z] = alphabet.substring(i - 1, i + 1);

You are taking the two element substring consisting of the i - 1th and the ith characters of alphabet. It looks like what you meant to do there is alphabet.substring(i, i + 1). In particular, this will cause issues if i = 0, since you will then be trying to take a substring starting at -1.