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Thread: exam revision question help please

  1. #1
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    Default exam revision question help please

    Consider the following program fragment that defines a self‐referential class:

    public class DrinkOrders
    {
    public String drinkDescription;
    public DrinkOrders next;
    public DrinkOrders(String d)
    {
    drinkDescription=d;
    next=null;
    }
    public addDrink(String d)
    {
    DrinkOrders o,c;
    o=new DrinkOrders(d);
    c=this;
    while (c != null)
    {
    c=c.next;
    }
    c.next=o;
    }
    
    public String toString()
    {
    return drinkDescription + toString();
    }
    }
    public class Harness
    {
    public static void main(String []args)
    {
    DrinkOrders myRound;
     
    myRound=new DrinkOrders("Beer");
    System.out.println(myRound.toString());
    /* ### */
    myRound.addDrink("Wine");
    System.out.println(myRound.toString());
    }
    }

    a. What will be displayed on the screen if the above program is compiled and run?
    Why?

    b. Assume that any compiler/logic errors that arose in part (a) above are corrected
    and, on execution, the annotated line (###) is reached without error. What
    would the output of the final println() method call be? Why?


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: exam revision question help please

    Please edit your post and fix the formatting for the code. Statements need to be indented to show the logic nesting level.
    All statements should NOT start in the first column.

    What will be displayed on the screen if the above program is compiled and run
    What happens when you compile and run the code? It seems silly to talk about it when it is so easy to do.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: exam revision question help please

     
    public class DrinkOrders
    {
    	public String drinkDescription;
    	public DrinkOrders next;
    	public DrinkOrders(String d)
    	{
    		drinkDescription=d;
    		next=null;
    	}
    	public addDrink(String d)
    	{
    		DrinkOrders o,c;
    		o=new DrinkOrders(d);
    		c=this;
    		while (c != null)
    		{
    			c=c.next;
    		}
    		c.next=o;
    	}
    
    	public String toString()
    	{
    		return drinkDescription + toString();
    	}
    }
     
    public class Harness
    {
    	public static void main(String []args)
    	{
    		DrinkOrders myRound;
     
    		myRound=new DrinkOrders("Beer");
    		System.out.println(myRound.toString());
    		/* ### */
    		myRound.addDrink("Wine");
    		System.out.println(myRound.toString());
    	}
    }

    I tried to compile but cannot thanks

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: exam revision question help please

    Please copy the full text of the error messages and paste it here.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: exam revision question help please

    error: invalid method declaration; return type required
    error: illegal character: \8230

    --- Update ---

    line 10, line 21

  6. #6
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    Default Re: exam revision question help please

    Which lines are line 10 and 21?

    Check on line 10: is your method declared correctly? Does it state on its declaration line that it will return anything?
    Check on line 21: do you have some characters in your file that simply don't belong there?

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