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Thread: program loops never ending

  1. #1
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    Default program loops never ending

    My code compiles correctly. After entering the employee name, it repeats Enter hourly rate without letting me input data. Where have I gone wrong?
       // Payroll Program Part 2
       import java.util.Scanner; //uses class scanner
       import java.io.PrintStream;
     
       public class PayrollProgramPart2
       {
     
       // begin execution
       public static void main( String args[] )
          {
          // create scanner
     
          Scanner input = new Scanner(System.in );
     
          double number1; //input
          double number2; //input
          double sum; //sum of 1 and 2
          boolean end = false; //is input stop
          while (end == false) // end is false proceed
             {
             number1 = -1; both are -1
             number2 = -1; both are -1
             String name;
             System.out.print( "Enter Employee name:" ); //prompt
             name = input.nextLine();
             if(name.toLowerCase() == "stop")
                end = true; // stop is detected
       while loop while(number1<0) // since I set it at -1 ahould loop until a postive number is put in
     
                System.out.print( "Enter hourly rate:" ); //prompt
                number1 = input.nextDouble(); // read first number
     
                while(number2 < 0) // same as number1
                {
                   System.out.print( "Enter number of hours:" ); // prompt
                   number2 = input.nextDouble(); // read second number
                }
             sum = number1 * number2; //multiply numbers
     
             System.out.printf (" Weekly Pay for%S is $ %.2f\n", name, sum); // Wage 
     
       } // end 
          } // end
             } //end
                } // end
    Last edited by copeg; November 27th, 2010 at 04:09 PM. Reason: Code tags


  2. #2
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    Default Re: program loops never ending

    Hello Ccogh05.

    Welcome to the forums.

    Whats with all the while loops? Take a look at this example:

    import java.util.Scanner;
     
    public class PayrollProgramPart2_jpf {
     
    	/**
    	 * JavaProgrammingForums.com
    	 */
    	public static void main(String[] args) {
     
    		Scanner input = new Scanner(System.in);
    		System.out.print("Enter Employee name:");
     
    		while(input.hasNext()){
    			String strInput = input.next();
    			if(strInput.equals("stop")){
    				System.exit(0);
    			}
     
    			String name = strInput;
     
    			System.out.print("Enter hourly rate:");
    			double number1 = input.nextDouble();
     
    			System.out.print("Enter number of hours:"); 
    			double number2 = input.nextDouble();
     
    			double sum = number1 * number2;
    			System.out.printf("Weekly Pay for%S is $ %.2f\n", name, sum);
     
    		}
     
    	}
     
    }
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  3. #3
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    Default Re: program loops never ending

    Quote Originally Posted by Ccogh05 View Post
    My code compiles correctly. After entering the employee name, it repeats Enter hourly rate without letting me input data. Where have I gone wrong?
       // Payroll Program Part 2
       import java.util.Scanner; //uses class scanner
       import java.io.PrintStream;
     
       public class PayrollProgramPart2
       {
     
       // begin execution
       public static void main( String args[] )
          {
          // create scanner
     
          Scanner input = new Scanner(System.in );
     
          double number1; //input
          double number2; //input
          double sum; //sum of 1 and 2
          boolean end = false; //is input stop
          while (end == false) // end is false proceed
             {
             number1 = -1; both are -1
             number2 = -1; both are -1
             String name;
             System.out.print( "Enter Employee name:" ); //prompt
             name = input.nextLine();
             if(name.toLowerCase() == "stop")
                end = true; // stop is detected
       while loop while(number1<0) // since I set it at -1 ahould loop until a postive number is put in
     
                System.out.print( "Enter hourly rate:" ); //prompt
                number1 = input.nextDouble(); // read first number
     
                while(number2 < 0) // same as number1
                {
                   System.out.print( "Enter number of hours:" ); // prompt
                   number2 = input.nextDouble(); // read second number
                }
             sum = number1 * number2; //multiply numbers
     
             System.out.printf (" Weekly Pay for%S is $ %.2f\n", name, sum); // Wage 
     
       } // end 
          } // end
             } //end
                } // end

    Just a word of advice, you should probably reduce your WHILEs to a minimum... since the higher the number of loops is the more complex your algorithm is. As for the ending problem, whenever you want to check if two strings you need to use the equals methods, == will only check if the objects' reference is the same. So in your case you'd have name.toLowerCase().equals("stop") or name.equalsIgnoreCase("stop'')

  4. #4
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    Default Re: program loops never ending

    Another way might be to change the while loop to

    while(!strInput.equals("stop"))

    and get rid of if block.
    Last edited by javapenguin; January 20th, 2011 at 01:51 PM.

  5. #5
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    Default Re: program loops never ending

    ok i agree with the previous posts with getting rid of the while statements.

    but as is, i found your error...

    while loop while(number1<0)
    // there needs to be a { here, otherwise only the next line is associated with the while loop
    System.out.print( "Enter hourly rate:" ); 
    number1 = input.nextDouble(); 
    // and here needs to be the } so the program knows that this is the intended stop point

    so basically when the program reads that number1<0 it then goes on to read the System.out.print line, and since there is no brackets the program assumes that is the only line you want to associate with the while loop therefore the next line is never reached and you have created a forever loop

    hope that helps

  6. #6
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    Default Re: program loops never ending

    I agree with previous posts. Too many while loops complicate your algorithm.

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