Morse Code to English

[Saad Salman]

need to convert morse code into English but without using arrays or maps
need help!!

import java.util.Scanner;

public class newReverseMorseCodeProgram {
  public static void main (String [] args) {
   
    String code;
    char j = 0;
    int 
    
    System.out.println("Type the code to be converted");
    code = new Scanner(System.in).nextLine(); 
    
    if (code.equals( ".---")) {
      System.out.println("A");
    }
    else if (code.equals( "-...")) {
      System.out.println("B");
    }
    else if (code.equals( "-.-.")) {
      System.out.println("C");
    }
    else if (code.equals( "-..")) {
      System.out.println("D");
    }
    else if (code.equals( ".")) {
      System.out.println("E");
    }
    else if (code.equals( "..-.")) {
      System.out.println("F");
    }
    else if (code.equals( "--.")) {
      System.out.println("G");
    }
    else if (code.equals("....")) {
      System.out.println("H");
    }
    else if (code.equals("..")) {
      System.out.println("I");
    }
    else if (code.equals(".---")) {
      System.out.println("J");
    }
    else if (code.equals( "-.-")) {
      System.out.println("K");
    }
    else if (code.equals( ".-..")) {
      System.out.println("L");
    }
    else if (code.equals( "--")) {
      System.out.println("M");
    }
    else if (code.equals ("-.")) { 
      System.out.println("N");
    }
    else if (code.equals( "---")) {
      System.out.println("O");
    }
    else if (code.equals( ".--.")) {
      System.out.println("P");
    }
    else if (code.equals( "--.-")) {
      System.out.println("Q");
    }
    else if (code.equals( ".-.")) {
      System.out.println("R");
    }
    else if (code.equals("...")) {
      System.out.println("S");
    }
    else if (code.equals("-")) {
      System.out.println("T");
    }
    else if (code.equals("..-")) {
      System.out.println("U");
    }
    else if (code.equals("...-")) {
      System.out.println("V");
    }
    else if (code.equals(".--")) {
      System.out.println("W");
    }
    else if (code.equals("-..-")) {
      System.out.println("X");
    }
    else if (code.equals("-.--")) {
      System.out.println("Y");
    }
    else if (code.equals ("--..")) {
      System.out.println("Z");
    } 
    else if (code.equals (" ")) {
      System.out.println(" ");
    }
    else 
      System.out.println(" not defined ");
  }
}

[Mike. J. Thompson]

What is your question? Is the code failing to compile, is it not behaving the way you want it to etc?

[Campbell Ritchie]

Welcome to the Ranch

Always use the code button; I have edited your code with it and doesn't it look better
As you have been told, you need to tell us what is going wrong otherwise we don't know what to suggest.

[salvin francis]

Saad Salman wrote:... need to convert morse code into English but without using arrays or maps

Why ?

[Campbell Ritchie]

salvin francis wrote:. . . Why ?

Because some teachers don't explain their requirements very well. The idea is to demonstrate that the students can write if‑elses. So you tell them not to use Maps, which would usually be regarded as poor programming.

I would have used a switch statement myself.

[salvin francis]

Campbell Ritchie wrote:I would have used a switch statement myself.

I would have used a HashMap

[Jelle Klap]

salvin francis wrote:

Campbell Ritchie wrote:I would have used a switch statement myself.

I would have used a HashMap

The requirements specifically prohibit the use of Map implementations.

[Campbell Ritchie]

Of course a Map is the best solution. So would be a MorseCharacter class, but the OP is being tested on writing if elses.

/**
 * blahblabblah immutable
 * yadayadayada
 */
public final class MorseCharacter
{
   private final String code;
   private final char letter;
   private final int hash;

   public MorseCharacter(String code, char letter)
   {
      if (!/* code matches dots and dashes only */ ||
            !(letter >= 'a' && letter <= 'z' || letter >= 'A' && letter <= 'Z'))
      {
         throw new IllegalArgumentException(...);
      }
      this.code = code;
      this.letter = letter;
      hash = 131071 + code.hashCode() * 31 + letter % 0x20;
   }

   @Override
   public String toString()
   {
      return code + " = " + letter;
   }

   public String getCode()
   {
      return code;
   }

   public char getLetter()
   {
      return letter;
   }

   /**
    * blahblabblah @return if ... and considers uppercase and lowercase letters as equal.
    */
   @Override
   public boolean equals(Object ob)
   {
      return ob == this ||
                ob instanceof MorseCharacter &&
              ((MorseCharacter)ob).code.equals(this.code) &&
              ((MorseCharacter)ob).letter %0x20 == this.letter % 0x20;
   }

   @Override
   public int hashCode()
   {
      return hash;
   }
}

MorseCharacter eMorse = new MorseCharacter(".", 'e');
morseMap.put(eMorse.getCode(), eMorse.getLetter());
reverseMorseMap.put(eMorse.getLetter(), eMorse.getCode());

I used 131071 for hash because it is a Mersenne prime. The %0x20 bit means you get the same hash code for 'A' and for 'a'.

[Stephan van Hulst]

I would have used an enum.

[Stephan van Hulst]

Campbell Ritchie wrote:I used 131071 for hash because it is a Mersenne prime. The %0x20 bit means you get the same hash code for 'A' and for 'a'.

My personal preference would be to store the letter in canonical form (for instance, in uppercase), and using Objects.hash(code, letter) to generate the hash code.

[salvin francis]

Stephan van Hulst wrote:I would have used an enum.

I am a bit curious about this in enums .. were you still going to use switch cases ?
I was thinking of its in lines of valueOf() method, but then his values were dots and dashes.

maybe like this:

public class Test {
	static char alphabets[] = {'A'};
	enum MORSE{XYYY}
	
	public static void main(String[] args) {
		String hash = ".---";
		String replaced = hash.replace('.', 'X').replace('-', 'Y');
		System.out.println(alphabets[MORSE.valueOf(replaced).ordinal()]);
	}
}

[Tim Holloway]

So if I build a trinary tree whose branches are "dot", "dash" and "terminate", does that count as a map?

This, BTW is why I flunk employment programming aptitude tests. It's never one of the "right" answers.

[Stephan van Hulst]

If the assignment is to not use any arrays at all, then yes, I would work with a switch statement. If not, then the values() method can be used. The general outline would be something like this:

enum MorseCharacter {

  A    ( 'A', ".-"    ),
  B    ( 'B', "-..."  ),
  
  ZERO ( '0', "-----" );

  private final char letter;
  private final String sequence;

  private MorseCharacter(char letter, String sequence) {
    this.letter = letter;
    this.sequence = sequence;
  }

  char letter() {
    return letter;
  }

  String sequence() {
    return sequence;
  }

  static MorseCharacter forLetter(char letter) {
    // TODO: either switch or iteration over values.
  }

  static MorseCharacter forSequence(String sequence) {
    // TODO: either switch or iteration over values.
  }
}

[Campbell Ritchie]

Tim Holloway wrote:So if I build a trinary tree whose branches are "dot", "dash" and "terminate", does that count as a map? . . .

Surely that is a Huffman code

[Campbell Ritchie]

I think, Stephan, you are right about Objects#hash.
I don't think there is any chance of a null String getting into my class, is there?

[Tim Holloway]

Finite State Machine? I've used Antlr since it was still known as the Purdue Compiler Construction Toolset.

I know, I know I don't get the job.

[Mike. J. Thompson]

Hi Saad.

Please don't ask Java questions in Private Messages. Post the question in the main thread so everyone can see and contribute.

For the benefit of others here, Saad would like to know why the code works for single characters but not for multiple characters.

[Mike. J. Thompson]

The reason the code only works for single characters is because you are comparing the entire input String against the code for each character. If the string does not exactly match the code for a single character only then it won't do anything.

You are going to have to find an approach to take your string and see if it starts with the code for a character. You will then need to discard the part of the input used and repeat for the next character.

[Mike. J. Thompson]

Oh, and your code for A appears to be the same as your code for J. I think you have made an error somewhere.