How do I loop this code , so that the program repeats it self ?

Question

import java.util.Scanner;

public class pigLatin {

public static void main(String[] args)
{

Scanner tread = new Scanner(System.in); //
String word, pig;
char first;


System.out.print("Please Enter English Word: ");
word = tread.next();
word = word.toLowerCase();
System.out.println(word);

first = word.charAt(0);
if (first == 'a' || first == 'e' || first == 'i' ||
first == 'o' || first == 'u') // vowel
pig = word + "hay";
else
pig = word.substring(1) + word.charAt(0) + "ay";



System.out.println("PIG-LATIN : " + pig);



}
}

Answer 1

Hi Laura, there are two parts to my answer:

 

1) Use a do/while loop and break on the String "word" being null.

do {

System.out.print("Please Enter English Word: ");
word = tread.next();
word = word.toLowerCase();
System.out.println(word);

first = word.charAt(0);
if (first == 'a' || first == 'e' || first == 'i' ||
first == 'o' || first == 'u') // vowel
pig = word + "hay";
else
pig = word.substring(1) + word.charAt(0) + "ay";



System.out.println("PIG-LATIN : " + pig);
} while ( word != null );

 

 

2) The issue with just the above fix is that you're still left with an issue if the user doesn't type any characters and just hits enter. The line "tread.next()" will fail. Also if the user types in an EOF character (on Mac it would be Ctrl+D). In addition, if the user were to type multiple words, it would not behave as intended. Adding the following will fix this:

 

public static void main(String[] args)
{

Scanner tread = new Scanner(System.in); //
String word = "", pig;
char first;
boolean next_line_exists;

do
{
System.out.print("Please Enter English Word: ");

// Read line; make sure it is not empty
next_line_exists = tread.hasNextLine();
if ( next_line_exists )
{
String line = tread.nextLine();

if ( !line.isEmpty() )
{
// Split the String and grab first word
String[] word_array = line.split(" ");
word = word_array[0];
word = word.toLowerCase();
System.out.println(word);

first = word.charAt(0);
if (first == 'a' || first == 'e' || first == 'i' ||
first == 'o' || first == 'u') // vowel
pig = word + "hay";
else
pig = word.substring(1) + word.charAt(0) + "ay";

System.out.println("PIG-LATIN : " + pig);
}
}
} while ( next_line_exists );

}

 

Hope this helps!

 

Alex

Answer 2

I'm not familiar with Java, so if you're looking for exact syntax, sorry, I can't help there. I can, however, give you a conceptual answer.

 

If you want the program to repeat for a set number of times (let's say you always want to create 8 words in pig-latin) then you would put everything from "System.out.print("Please Enter English Word: "); " to "System.out.println("PIG-LATIN : " + pig);" inside of a for loop.

 

If, however, you want the program to run until the user stops it, you will need something just a little more complicated. There are quite a few ways you could go about this. Personally, I would do the following:

1. Pick a word (I'll chose "STOP") for the user to enter when they wish to stop the program. At the top of the program, print a message that explains this.
2. Create a while loop: I would put the block of text that changes word to pig Latin, as well as the line that prints the result, inside of a while loop, with the condition being "While word does not equal "STOP" "
3. Copy and Paste: There are more sophisticated ways to do this, but I would just copy the block of text that gets a new word from the user and paste at the end of the while loop. NOTE: I said copy, not cut. In this implementation we are using the block both outside of the while loop, exactly where it is now, and at the bottom of the while loop.

Why this works:

We want to check that the user has not entered "STOP" before we convert the word to pig Latin, but after we get a new word from the user. We need our check to be in the middle of the process, then. That is a problem in the base case, the first time we run the process, because we have to get a word from the user before we can begin the conversion process. This is why that piece of code has to be both above and within the while loop. (There are other ways to write this to avoid repeating code, but personally I like this solution because it works and makes sense to me.)

 

I hope that helped! I'm not an expert by any means, and again I don't know Java to be able give you a more precise answer, so sorry if you were just looking for how to write loops in Java!! Let me know if you have any questions. :)

 

--Laura