1. CS305J Introduction to Computing
Discussion Section
Week 12

2. Announcements No lab 11, no A Pair assignment has changed
lab 11 counts for 10 out of 100 total
Pair assignment has changed
check at the discussion board
Set game rules

3. Recap from Lab 10 Input racecar testing a end Output
racecar is a palindrome
testing is not a palindrome
a is a palindrome

4. To-do List Repeat these three steps until “end”
Read a word from file input
Check if the word is palindrome or not
Output to the terminal if the word is (not) a palindrome
print the result
read from file
check palindrome
stop if “end”

5. Methods Method 1 (nextWord) Method 2 (isPalindrome)
parameter: Scanner file
return: String word
Method 2 (isPalindrome)
parameter: String word
return: boolean result
Method 3 (printResult)
parameter: boolean result, String word
return: void
read from file
word
check palindrome
result
print the result

6. Use Java API BlueJ->Help->Java Class Libraries
nextWord = next() in Scanner class
printResult = System.out.print(word)
printResult
nextWord
isPalindrome
stop if “end”
Main method only contains the “logic” part.
while loop stops at “end”
calls other methods

7. Class Palindrome public static boolean isPalindrome(String word)
return true if the word is a palindrome
public static void main(String[])
while (word is not end)
read word using next()
call isPalindrome(word)
print the result

8. Recap from TicTacToe Input moves Output for each move,
1,1
0,1
1,0 .
Output
for each move,
print error if illegal move
display the board
announce the winner

9. Design with many classes
What objects? (Classes)
What to remember? (Instance Variables)
How the classes interact?
game
instance variables:
int turn, board b
b.display()
b.move(x, y, turn)
board
instance variable:
int[][] board
public void display()
public boolean move(int x, int y, int turn)

10. Design each Class Classes: game, board Instance variables
What to do in each class? (Methods)
game
receive user input for the move
announce the winner
game
instance variables:
int turn, board b
b.display()
b.move(x, y, turn)
board
instance variable:
int[][] board
public void display()
public boolean move(int x, int y, int turn)

11. Class Game private int turn private board myBoard
public static void main(String[])
initialize myBoard
while (there is no winner)
read (x,y) location for the next move
myBoard.move(x, y, turn)
myBoard.display()
myBoard.isWin()
change the turn
read the move
(x,y)
move on the board
true/false
display board
check winner
false
change the turn

12. Class Board private int[][] board private boolean winner
public boolean move(int x, int y, int turn)
return false if the move is not allowed
set winner to be true if this is the winning move
public void display()
display the current board
public boolean isWin()
return true if instance variable winner is true

13. Connect Four Turn-in by 10pm today
Cover page: names and discussion sections
Input/Output
Class Interaction Design
Design for each class (instance variables, methods)
Diagram for the logic in the main method
Turn-in by 10pm today
rtf, doc, ppt, ps, pdf
hard copy in homework box in TAY