ITEC 120 2009spring ibarland nokie jmdymacek

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lab06b
Ordering Donuts

The fancy bread shop, Oh Bonnie Pain, sells delicious Sugarbomb Donuts for 85 cents each. In order to seem european, they will list their prices using a comma as the decimal-separator: that is, “$4,50” rather than “$4.50”.

Your task: write a class DonutShop which has just one method, which gives a fancy-sounding message when somebody orders doughnuts.

class DonutShop {

  /** Respond to a donut order, at Oh Bonnie Pain.
   * @param numDonuts The number of donuts ordered.  Non-negative.
   * @return A sophisticated-sounding message reporting the total price.
   *         (see test cases).  
   */
  String donutOrderriere( int numDonuts ) {
    return "You'll replace this stub function.";
    }



  /** The price of one donut, *in pennies*. */
  private int centsPerDonut;

  /** Construct a donut shop which charges 85 cents for a donut: */
  public DonutShop() {
    this.centsPerDonut = 85;
    }


  }

class DonutShopTester {
  public static void main( String[] args ) {
    DonutShop auBonP = new DonutShop();

    System.out.println( "Ordering 10 donuts; the cashier's reply is:");
    System.out.println( "Actual:   \"" + auBonP.placeOrderriere(10) + "\"" );
    System.out.println( "Expected: \"10 sucrebombe donuts will cost $8,50.  Merci!\"" );

    System.out.println( "Ordering 13 donuts; the cashier's reply is:");
    System.out.println( "Actual:   \"" + auBonP.placeOrderriere(13) + "\"" );
    System.out.println( "Expected: \"13 sucrebombe donuts will cost $11,05.  Merci!\"" );

    System.out.println( "Ordering 2 donuts; the cashier's reply is:");
    System.out.println( "Actual:   REPLACE THIS WITH A METHOD CALL" );
    System.out.println( "Expected: REPLACE THIS WITH EXPECTED ANSWER" );

    System.out.println( "Ordering 1 donut; the cashier's reply is:");
    System.out.println( "Actual:   REPLACE THIS WITH A METHOD CALL" );
    System.out.println( "Expected: REPLACE THIS WITH EXPECTED ANSWER" );
    }
  }

• It is important to be grammatically correct.

  hint: To check whether or not a number n is equal to 1, use (n==1) as the condition in an if-else statement.

• Note that placeOrderriere returns a message; it should not call System.out.println! (However, somebody who calls this method — like the test-driver — might choose to print the String this method gives them back.)
• Do not use double to represent prices; Instead, use ints. In fact, if you have an int number of pennies (e.g. 850), then generating a string like "$8,50" is extremely similar to the method getLengthMMSS from yesterday's lecture.

If you finish…

The above task really has two different parts: constructing the text-message, and converting a price into a fancy-euro-format. Modify your code by adding a second methods: priceInEuroFormat (which only deals with prices, and has nothing to do with donuts). Then modify your method donutOrderriere so that it calls priceInEuroFormat, passing in a price.

This version of the program behaves the same as before, but is better because it will let future users convert other (non-donut) prices into this format.

And if you finish that too:
Make a more general method priceInAnyFormat:

  System.out.println( "Expect \"$8.50\": \"" + priceInAnyFormat( 850, "$", "." ) + "\"" );
  System.out.println( "Expect \"USD8,50\": \"" + priceInAnyFormat( 850, "USD", "," ) + "\"" );
  System.out.println( "Expect \"£8x50\": \"" + priceInAnyFormat( 850, "£", "x" ) + "\"" );

• Confusing 0.85 dollars with 0.85 cents.
• Forgetting about % and /, and saying “I don't know how to get Java to print doubles using a comma”.
• Missing the singular vs plural, for 1 donut.
• Whoops -- lecture introduced “<”, but not “==”.

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©2009, Ian Barland, Radford University Last modified 2009.May.06 (Wed)

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