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Thread: Problem while implementing a basic user interface menu

  1. #1
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    Default Problem while implementing a basic user interface menu

    Hey, I need to create a basic user interface menu. My code complies, however it doesnt seem to work properly. Heres the code-
    import java.util.*;
     
    public class Program3
    {
    	public static void main(String[ ] args)
    	{
    		//declare variables
     
    		String Paren = "";
    		ParenExpression fullParen = new ParenExpression(Paren);
    		Scanner kb = new Scanner(System.in);
    		int response;
     
    		//do while loop that controls program
    		System.out.println("Welcome to the Program3");
     
    		do
    		{
    			//show the menu
    			System.out.println("\n\nChoose an option");
    			System.out.println("\t1\tCreate a new fully parenthesized expression");
    			System.out.println("\t2\tPrint the expression");
    			System.out.println("\t3\tPrint what it evaluates to");
    			System.out.println("\t4\tPrint the postfix equivalent");
    			System.out.println("\t5\tQuit");
     
    			//get the user response to menu
    			try
    			{
    				response = kb.nextInt();   //get it
    			}
    			catch(InputMismatchException e)
    			{
    				response = -1;    //something illegal
    				kb.nextLine();   //flush it
    			}
     
    			//do a logic "branch" depending on their response
    			try
    			{
     
    				if (response == 1)
    				{
     
    					//prompt user
    					System.out.print("\nPlease enter a fully parenthesized expression: ");
    					Paren = kb.nextLine();
    					kb.nextLine();
    					fullParen = new ParenExpression(Paren);
     
    				}
    				else if (response == 2)
    				{
    					System.out.println(fullParen);
    				}
    				else if (response == 3)
    				{
    					System.out.println(fullParen.evaluate());
    				}
    				else if (response == 4)
    				{
    					System.out.println(fullParen.asPostfix());
    				}
    				else
    					System.out.println("\nInvalid input - try again");
    			}
     
    			catch (Throwable theException)  //...catches everything (since every one is a subclass of Throwable)
    			{
    				System.out.println("got something - " + theException);
    				theException.printStackTrace();       //prints the calling sequence up to the exception
    			}
    		}
    		while (response != 5);
    	}
    }
    I think the problem might come from the flushing in the first response around lines 46-49, however I'm not sure. Those lines of code are -
    					System.out.print("\nPlease enter a fully parenthesized expression: ");
    					Paren = kb.nextLine();
    					kb.nextLine();
    					fullParen = new ParenExpression(Paren);
    Any tips would be appreciated


  2. #2
    mmm.. coffee JavaPF's Avatar
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    Default Re: Problem implementing a user interface using a menu

    Hello Rastabot and welcome to the Java Programming Forums

    What is ParenExpression?

    I can't compile the above code.
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  3. #3
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    Default Re: Problem implementing a user interface using a menu

    Never mind I just figured it out. My flush line was after my variable line, so what I typed in wasn't going in to any variable.
    Last edited by Rastabot; April 3rd, 2009 at 03:26 PM.

  4. #4
    mmm.. coffee JavaPF's Avatar
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    Default Re: Problem implementing a user interface using a menu

    Quote Originally Posted by Rastabot View Post
    Never mind I just figured it out. My flush line was after my variable line, so what I typed in wasn't going in to any variable.
    Well spotted.
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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