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Thread: do while loop terminating to early

  1. #1
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    Default do while loop terminating to early

    Hi all,

    I am a newbie to programming and this is my first attempt to write a java program. I calculating the root of a integer that is supplied by the user, this then calls a method that does the calculation. The user is then prompted to either continue to calculate more root calculations or terminate the program, in this case the program provides a "Thank you for participating" message. This is done by either providing a "y" or "n"
    Even if the user enters a "y" to continue, the loop terminates. This is the code that I have written:

    import java.io.*;
     
    public class root {
     
    	public static int calcRoot(int a)
    	{
    		// if (a != integer)
    		// throw new intErrorExecption("Input must be a integer");
    		return a=(int) Math.sqrt(a);
    	}
     
     
    	public static void main(String[] args) throws IOException 
    	{
    		int tempInt=0;
    		String sCont;
    		BufferedReader stdin = new BufferedReader
    			      (new InputStreamReader(System.in));
    		// try
     
    		do 
    		{
     
    		System.out.print("Enter integer: ");
    		System.out.flush();
    		tempInt=Integer.parseInt( stdin.readLine());
     
    		// }  
     
    	       // catch (intErrorExecption e)
    	       // {
     
     
    	       System.out.println("The square root of " +tempInt+ " is "+calcRoot(tempInt));
     
     
     
    	       System.out.print("Do you want to continue? (y / n): ");
     
     
    	       System.out.flush();
     
     
    			/* Code to check if the read line provided y or n, if y continue loop else
    			 *  exit loop and print "Thank you for participating"
    			 */
     
    			sCont=stdin.readLine();
    			 if(sCont=="n")
    			    {
    			    	break;
     
    			    }
     
     
    			} while	(sCont == "y");	//loop is terminated here even though variable sCont is set here for string value "y"
     
     
     
    		System.out.println("Thank you for participating");
     
     
    	}
     
    }

    I am greatfull if someones spots the error of my algorithm.

    thanks
    -Sohail


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: do while loop terminating to early

    Don't use == to compare Strings. Use the equals() method instead. The == operator determines whether two Objects are the same instance, the equals() method checks for semantic equality.
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
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  3. #3
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    Default Re: do while loop terminating to early

    Thanks a lot, I altered my conditional and looping code to the following and it worked:

    do 
    		{
     
    		System.out.print("Enter integer: ");
    		System.out.flush();
    		tempInt=Integer.parseInt( stdin.readLine());
     
    	       System.out.println("The square root of " +tempInt+ " is "+calcRoot(tempInt));
     
     
     
    	       System.out.print("Do you want to continue? (y / n): ");
     
     
    	       System.out.flush();
     
     
    			/* Code to check if the read line provided y or n, if y continue loop else
    			 *  exit loop and print "Thank you for participating"
    			 */
     
    			sCont=stdin.readLine();
    			 if(sCont.equals("n"))
    			    {
    			    	break;
     
    			    }
     
     
    			} while	(sCont.equals("y"));
     
     
     
    		System.out.println("Thank you for participating");

  4. #4
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: do while loop terminating to early

    For Strings, you might also want to check out the equalsIgnoreCase() function.
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
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