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Thread: There must be a better way...

  1. #1
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    Default There must be a better way...

    But I don't know what it is. I'm a student and this is my first (university) class in Java programming.

    Basically, what I'm trying to do is write a simple tip calculator. The trouble is with how my instructor wants it done. He wants the user to be presented with this as the tip types:

    1- 10%
    2- 15%
    3- 20%
    4- 25%

    and have the user input 1-4 instead of, say, "15" or "0.15". We haven't really done any examples like this in class so I'm not sure how to assign the 1-4 to each percentage. Complicating matters (and my math) is that we can only use integers; no double or float. I declared my variables as;

    int tipRate1 = 5 + (1 * 5);
    int tipRate2 = 5 + (2 * 5);
    int tipRate3 = 5 + (3 * 5);
    int tiprate4 = 5 + (4 * 5);

    and the base tip rate is 5 + tip type * 5. I know the math is right, but I'm not sure how to assign the values 1-4 AND the equation without listing the tip types twice- once to assign the base tip rate equation and again to assign the input value to it. Does that make sense? Is there a way to combine that into one line per tip type so it looks cleaner and more efficient?

    The other thing I'm having trouble with is how to get the tip amount. I know I have to do something like this;

    (foodBill + barTab)*100 to get the bill total in cents and then somehow get it to calculate the tip in the same line without using decimals. My instructor wants to output as, for example, "Your tip should be __dollars and __cents." I'm not sure how to turn it back into dollars and have a remainder, much less output as words and not just as a number.

    Anyways, it's not due until Feb 1st, but I've spent a lot of hours working on it for the last week and I've finally had to break down and seek some guidance. I'm getting a tad frustrated and feel like there's a simple solution I'm just not seeing. If anyone has some suggestions to point me in the right director, that would be fantastic!

  2. #2
    Think of me.... Mr.777's Avatar
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    Default Re: There must be a better way...

    Welcome RockDoc to Java Programming Forums. Don't forget to read the rules.
    Well, to accomplish this assignment, you must have to first look at Scanner class in java. When you are done with it, move on to the conditional statements and might be you need loop statements as well. So, according to my point of view you only need these 3 things to complete your assignment.
    Good Luck and if you stuck anywhere, let us know, we will be pleased to help you but not spoon feed.

  3. #3
    Super Moderator Norm's Avatar
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    Default Re: There must be a better way...

    we can only use integers
    That will require you to work in pennies vs dollars.
    a way to combine that into one line
    Look at using an array to hold the rates and use the type as an index

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    Default Re: There must be a better way...

    Honestly, I'm loving the idea of using an array, but I cannot. No loop or "if/else" statements either. My instructor gave us a very short list of methods we can use to accomplish this. He wants the input done using JOptionPane and Scanner (I understand JOptionPane completely, Scanner I'm less sure of so I've been reading more about it), and output using JOptionPane and echoed with System.out.println (no troubles there).
    Inputting numbers has to be done as a string and converted to an integer with parsing tools. I understand that I need to convert all the dollar amounts to cents before performing any calculations because I have to use whole numbers. Complicating matters is that I'm expected to add a command that will calculate the tip on either the base rate*the fod bill OR (the base rate - 5%) * the total of the food bill and bar tab...whichever is larger. That I have no idea how to do without using an if statement. ETA: Never mind. That's done like this, correct? tipTotal = (foodBill+barTab)*tipRate/100

    Just to clarify, I don't want anyone to give me the answers or specific code. Sorry if it sounded like that. I really do want to learn the material and understand how the programs work, or I'm going to be in big trouble when the exams roll around.

    I'm going to try recoding this in Scanner class and report back. I think I've almost got it figured out.
    Last edited by RockDoc; January 28th, 2012 at 09:02 PM.

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    Super Moderator Norm's Avatar
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    Default Re: There must be a better way...

    whichever is larger
    How do you detect that without using an if statement? Did the instructor give an clues?

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    Default Re: There must be a better way...

    How do you detect that without using an if statement? Did the instructor give an clues?
    I'm just starting Java too, so my solution may be really ugly. For figuring out which one is larger you could use interger division to produce which tip is larger. It's a roundabout way, and I'm sure there's something more elegant.

    Ex.
    int tipTotal1 = 5 ;
    int tipCompare1 = tipTotal1/tipTotal2 ;

    int tipTotal2 = 2 ;
    int tipCompare2 = tipTotal2/tipTotal1 ;

    int Tip = ((tipCompare1/tipCompare1) * tipTotal1 ) + ((tipCompare2/tipCompare2) * tipTotal2 ) ;

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    Default Re: There must be a better way...

    int Tip = ((tipCompare1/tipCompare1) * tipTotal1 ) + ((tipCompare2/tipCompare2) * tipTotal2 ) ;
    This statement will always return with either a runtime error or tipTotal1+tipTotal2.