March 31^st - Lecture 21

Collected Lab 18 from those who finished it. Others need to turn it in by noon tomorrow (Friday).

Distributed printouts of Hand.java and Driver.java from Lab17.

Went over Lab 17 in excrutiating detail

Established some design/coding guidelines in the process

• Declare for loop control variables in the loop so that they will be local to the loop
• Where methods exist to test whether a next element exists, use the method rather than catching an exception when accessing it fails.
• Avoid the use of numeric literals in the body of your code. If you think you need one, declare it as a constant at the top of your method or class. Then if it needs to be altered, it only has to be altered in 1 place
• When dealing with hands of cards, since the number of cards in the hand may vary, use the method .size() to determine the number of cards before retrieving them.
• Arrays was a class that we haven’t used before. When you saw the line Arrays.sort(cards); you should have gone to the java api to see what it was doing. We learned it has methods to sort all of the primitive types except boolean and that it has a method to sort Objects too.
• An if statement is a selection control structure.
• A loop statement is an iteration control structure.
• We talked about the fact the the suit order is clubs, diamonds, hearts, spades (alphabetical in English).
• When we tried to print out the Deck using System.out.println (Deck); the value that was printed was a hash code representing the address, not the address, and not the values in the Deck.
• We discussed that unless the Hand was printed before the element was removed, after the element was removed, and after another element was added, it was not possible to say that our code was correct.

Answered questions about programming assignment #4

• Stubs and Driver are due on Monday by midnight using submit... Read the specs carefully on what to include and what to submit.
• Stubs should have no code except headers and required return statements with appropriate values. The more comments in them the better. The stubs for Lab 17 are a good model.

Beatles.java (page 405 in our text)

· We discussed how ArrayList was declared without specifying the type of item to be in the list.

· We changed the second item to an int

· The warning compile message was the same whether all of the elements inserted into the list were of type String or whether one of them was an int

· We added a statement to check whether “Peter” was in the list before printing it in order to avoid an error

· We modified Beatles.java and created Beatles2.java where we specified the type of item to be in the ArrayList.