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Thread: Really need help..

  1. #1
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    Default Really need help..

    Can anyone explain why this code isn't working.. It's supposed to take a year and convert it to roman numerals.. I can't use returns.. "not allowed"..
    import java.util.Scanner;
    public class threedottwentysix {
    	public static void main(String[] args){
    	Scanner in = new Scanner(System.in);
    	System.out.println("Please Enter a year that is less than 3999: ");
    	String input = in.nextLine();
    	int digit = input.length();
    	String digitOne = "";
    	String digitTwo = "";
    	String digitThree = "";
    	String digitFour = "";
    	if (digit == 4){
    			int num1 = Integer.parseInt(input.substring(0, 1));
    			switch(num1){
    			case 1: digitOne = "M"; break;
    			case 2: digitOne = "MM"; break;
    			case 3: digitOne = "MMM"; break;
                                  }
                            }
    		else if (digit == 3)
                            { 
    			int num2 = Integer.parseInt(input.substring(1,2));
    			switch(num2)
                                {
    			case 1: digitTwo = "C"; break;
    			case 2: digitTwo = "CC"; break;
    			case 3: digitTwo = "CCC"; break;
    			case 4: digitTwo = "CD"; break;
    			case 5: digitTwo = "D"; break;
    			case 6: digitTwo = "DC"; break;
    			case 7: digitTwo = "DCC"; break;
    			case 8: digitTwo = "DCCC"; break;
    			case 9: digitTwo = "CM"; break;
                                }
                           }
    		else if (digit == 2)
                           {
    			int num3 = Integer.parseInt(input.substring(2,3));
    			switch(num3)
                                 {
    			case 1: digitThree = "X"; break;
    			case 2: digitThree = "XX"; break;
    			case 3: digitThree = "XXX"; break;
    			case 4: digitThree = "XL"; break;
    			case 5: digitThree = "L"; break;
    			case 6: digitThree = "LX"; break;
    			case 7: digitThree = "LXX"; break;
    			case 8: digitThree = "LXXX"; break;
    			case 9: digitThree = "XC"; break;
                               }
                            }
    		else if (digit == 1)
                               {
    			int num1 = Integer.parseInt(input.substring(3,4));
    			switch(num1)
                             {
    			case 1: digitFour = "I"; break;
    			case 2: digitFour = "II"; break;
    			case 3: digitFour = "III"; break;
    			case 4: digitFour = "IV"; break;
    			case 5: digitFour = "V"; break;
    			case 6: digitFour = "VI"; break;
    			case 7: digitFour = "VII"; break;
    			case 8: digitFour = "VIII"; break;
    			case 9: digitFour = "IX"; break;
                                }
                           }
    	if (digit == 3)
                      {
    			int num2 = Integer.parseInt(input.substring(1,2));
    			switch(num2) {
    			case 1: digitTwo = "C"; break;
    			case 2: digitTwo = "CC"; break;
    			case 3: digitTwo = "CCC"; break;
    			case 4: digitTwo = "CD"; break;
    			case 5: digitTwo = "D"; break;
    			case 6: digitTwo = "DC"; break;
    			case 7: digitTwo = "DCC"; break;
    			case 8: digitTwo = "DCCC"; break;
    			case 9: digitTwo = "CM"; break;
                                  }
                            }
    		else if (digit == 2)
                            {
    			int num3 = Integer.parseInt(input.substring(2,3));
    			switch(num3)
                                  {
    			case 1: digitThree = "X"; break;
    			case 2: digitThree = "XX"; break;
    			case 3: digitThree = "XXX"; break;
    			case 4: digitThree = "XL"; break;
    			case 5: digitThree = "L"; break;
    			case 6: digitThree = "LX"; break;
    			case 7: digitThree = "LXX"; break;
    			case 8: digitThree = "LXXX"; break;
    			case 9: digitThree = "XC"; break;
                                 }
                             }
    		else if (digit == 1)
                             {
    			int num4 = Integer.parseInt(input.substring(3,4));
    			switch(num4)
                                 {
    			case 1: digitFour = "I"; break;
    			case 2: digitFour = "II"; break;
    			case 3: digitFour = "III"; break;
    			case 4: digitFour = "IV"; break;
    			case 5: digitFour = "V"; break;
    			case 6: digitFour = "VI"; break;
    			case 7: digitFour = "VII"; break;
    			case 8: digitFour = "VIII"; break;
    			case 9: digitFour = "IX"; break;
                                   }
                             }
    	if (digit == 2)
                    {
    			int num3 = Integer.parseInt(input.substring(2,3));
    			switch(num3)
                                    {
    			case 1: digitThree = "X"; break;
    			case 2: digitThree = "XX"; break;
    			case 3: digitThree = "XXX"; break;
    			case 4: digitThree = "XL"; break;
    			case 5: digitThree = "L"; break;
    			case 6: digitThree = "LX"; break;
    			case 7: digitThree = "LXX"; break;
    			case 8: digitThree = "LXXX"; break;
    			case 9: digitThree = "XC"; break;
                                  }
                            }
    		else if (digit == 1) 
                            {
    			int num4 = Integer.parseInt(input.substring(3,4));
    			switch(num4)
                                  {
    			case 1: digitFour = "I"; break;
    			case 2: digitFour = "II"; break;
    			case 3: digitFour = "III"; break;
    			case 4: digitFour = "IV"; break;
    			case 5: digitFour = "V"; break;
    			case 6: digitFour = "VI"; break;
    			case 7: digitFour = "VII"; break;
    			case 8: digitFour = "VIII"; break;
    			case 9: digitFour = "IX"; break;
                                 }
                            }
    	if (digit == 1)
                            {
    			int num4 = Integer.parseInt(input.substring(3,4));
    			switch(num4)
                                   {
    			case 1: digitFour = "I"; break;
    			case 2: digitFour = "II"; break;
    			case 3: digitFour = "III"; break;
    			case 4: digitFour = "IV"; break;
    			case 5: digitFour = "V"; break;
    			case 6: digitFour = "VI"; break;
    			case 7: digitFour = "VII"; break;
    			case 8: digitFour = "VIII"; break;
    			case 9: digitFour = "IX"; break;
                                   }
                            }
    	System.out.print(digitOne + digitTwo + digitThree + digitFour);
    	}	
    }

    output:
    Please Enter a year that is less than 3999:
    1962
    M

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Really need help..

    code isn't working
    Can you explain what "isn't working" means?
    If there are errors, copy the full text of the error messages and paste it here.
    If the output is wrong, post the contents of the console from when the code is executed and explain what is wrong with it.

    Please edit your post and wrap your code with
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.

    One problem I see with being able to understand the posted code is its formatting.
    I see lots of hidden }} at the ends of statements making it hard to see the structure of the code.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Member Zyrion's Avatar
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    Default Re: Really need help..

    Instead of using all of those else if statements, could you try using nested switch statements?

  4. #4
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    Default Re: Really need help..

    See, my prof. taught us nested if statements and told me to do it that way.. I honestly don't know the correct format in nested switch statements.. I have a Java book but really isn't helpful for more complicated problems.. well.. complicated being relative..

  5. #5
    Super Moderator Norm's Avatar
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    Default Re: Really need help..

    You need to do more work on the program's design before continuing.
    How should a 4 digit number be converted? Look at doing it digit by digit.
    After doing the first digit, how should the program handle the next digit and the next.
    Now what if there are only 3 digits? How can some of the code used for the 4 digit number be used for the 3 digit number?
    And the same for the 2 digit number and the one digit number.

    Look at how to convert each of the following. Use a variable for getting the digits, not hardcoded values like in the posted code.
    1111
    111
    11
    1


    BTW The formatting of the code still has too many hidden }s at the end of statements.
    If you don't understand my answer, don't ignore it, ask a question.

  6. #6
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    Default Re: Really need help..

    When you say the "hardcoded values," do you mean the int num1 = Integer.parseInt(input.substring(1,2);? Isn't num1 considered a variable?

  7. #7
    Super Moderator Norm's Avatar
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    Default Re: Really need help..

    int num1 = Integer.parseInt(input.substring(1,2);
    The 1 and 2 are hardcoded values. They should be variables.
    If you don't understand my answer, don't ignore it, ask a question.