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Beginning Java Help Please

Discussion in 'Java' started by weber14, Feb 5, 2011.

  1. weber14

    weber14 New Member

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    Hi I'm new to Java. I am trying to write a program that allows the user to select a medium to calculate the speed of sound. The user will need to choose a medium (air, water, steel) & then input how far the sound wave will travel. I have to create a menu with the 3 options & have the program generate an error message if incorrect data is entered by the user. Below is my code. I keep getting an error back stating that there is a syntax error on token else. Any help is appreciated. Thanks.

    This is what I have so far. If I remove the else statements, the program runs, but when you input any letter for the medium, the program terminates.

    Code:
    import java.util.Scanner;	//import the Scanner class
    
    class Wave
    {
    	public static void main (String[] args)
    	{
    		double distance;	//distance variable
    		double time;	//time variable
    						
    		String medium;
    		char Air = 'a';
    		char Water = 'w';
    		char Steel = 's';
    		
    		Scanner in = new Scanner(System.in);
    		
    		System.out.println("Welcome to Sound Wave Calculator\n");
    		
    		System.out.println("Select the medium the sound wave will travel through.");	
    		System.out.println("	A	Air");
    		System.out.println("	W	Water");
    		System.out.println("	S	Steel");
    		medium = in.next();
    		Air = medium.charAt(0);
    		Water = medium.charAt(0);
    		Steel = medium.charAt(0);
    		
    		System.out.println("How far will the sound travel (in feet)?");
    			distance = in.nextDouble();
    			
    		char response1 = 0;
    		if ((response1 == 'a') || (response1 == 'A'))	//control condition
    		{
    			time = distance/1100;
    			System.out.print("The sound wave will travel" + time + "seconds");
    			medium = in.next();
    			response1 = medium.charAt(0);		//response is the first letter
    		}
    		
    		char response2 = 0;
    		else if ((response2 == 'w') || (response2 == 'W'))	//control condition
    		{
    			time = distance/4900;
    			System.out.print("The sound wave will travel" + time + "seconds");
    			medium = in.next();
    			response2 = medium.charAt(0);
    		}
    		
    		char response3 = 0;
    		else if ((response3 == 's') || (response3 == 'S'))
    		{
    			time = distance/16400;
    			System.out.print("The sound wave will travel" + time + "seconds");
    			medium = in.next();
    			response3 = medium.charAt(0);
    		}
    		else if (medium != 'a' && medium != 'w' && medium != 's')
    		{
    		System.out.println("Illegal entry. Aborting Program.");
    		System.out.println("Goodbye.");
    		}
    	
    		System.out.println("Goodbye");			//end of main
    	}
    }
     
    Last edited by a moderator: Feb 6, 2011
  2. virxen

    virxen New Member

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    i made some changes check it

    Code:
    import java.util.Scanner;    //import the Scanner class
    
    public class Wave{
        public static void main (String[] args)    {
            double distance=0;    //distance variable
            double time=0;    //time variable                
            //String medium;
            String Air = "a";
            String Water = "w";
            String Steel = "s";
            String response="";
            String Exit="e";
            Scanner in = new Scanner(System.in);
            System.out.println("Welcome to Sound Wave Calculator\n");
            while (!response.equalsIgnoreCase(Exit)){
                while (!response.equalsIgnoreCase(Air)   && !response.equalsIgnoreCase(Water) &&
                          !response.equalsIgnoreCase(Steel) && !response.equalsIgnoreCase(Exit)){
                    System.out.println("Select the medium the sound wave will travel through.");    
                    System.out.println("    A    Air");
                    System.out.println("    W    Water");
                    System.out.println("    S    Steel");
                    System.out.println("    E    Exit");
                    response = in.next();
                    if(!response.equalsIgnoreCase(Air)   && !response.equalsIgnoreCase(Water) &&
                       !response.equalsIgnoreCase(Steel) && !response.equalsIgnoreCase(Exit))
                        System.out.println("wrong choice please try again!!");
                }
            //Air = medium.charAt(0);
            //Water = medium.charAt(0);
            //Steel = medium.charAt(0);
                if (!response.equalsIgnoreCase(Exit)){
                    System.out.println("How far will the sound travel (in feet)?");
                    distance = in.nextDouble();    
                }
            //char response1 = 0;
                if (response.equalsIgnoreCase(Air))    {//control condition
                    time = distance/1100;
                    //System.out.println("The sound wave will travel " + time + " seconds");
                //medium = in.next();
                //response1 = medium.charAt(0);        //response is the first letter
                }
            //char response2 = 0;
                else if (response.equalsIgnoreCase(Water)){    //control condition
                    time = distance/4900;
                    //System.out.println("The sound wave will travel " + time + " seconds");
                //medium = in.next();
                //response2 = medium.charAt(0);
                }
            
        //    char response3 = 0;
                else if (response.equalsIgnoreCase(Steel)){
                    time = distance/16400;
                    //System.out.println("The sound wave will travel " + time + " seconds");
                //medium = in.next();
                //response3 = medium.charAt(0);
                }
            //else if (medium != 'a' && medium != 'w' && medium != 's')
            //{
            //System.out.println("Illegal entry. Aborting Program.");
            //System.out.println("Goodbye.");
            //}
                if (!response.equalsIgnoreCase(Exit)){
                    System.out.println("The sound wave will travel " + time + " seconds");
                    response="";
                }
            }
            System.out.println("Goodbye");            //end of main
        }
    }
    
     

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