CS51 - Fall 2009 - Lecture 4

  • exercise 3.11.2
       - Write the instructions for creating and positioning a 50 by 50 pixel FramedRect so that it is centered in any window.
       - Write the instructions for creating a Text object, that says "I am centered" and positions it so that it is centered in any window.

  • show basketball demo and code

  • show better basketball demo
       - what do we need to change?
          - instance variables
             - ball (oval, location and size)
          - how do we move the ball? (hint: think about scribble)
             - onMousePress - see if we're inside the ball
                - keep track of this somehow
                - boolean variables
             - onDrag
                - check if we're holding the ball
                - if so, move the ball (how do we do this?)
             - onRelease
                - check if we're carrying the ball
                - check if we're inside the hoop
                - if both true
                   - update score
                   - update display
                - what about the position of the ball?

  • show BetterBasketBall code
       - nested if statements
          - this seems awkward? What question are we asking here?
          - AND ('&&') and OR ('||')
          - change code

  • show Color4Scribbler demo
       - what is the difference between this version and scribbler?
          - randomly picking colors
             - RandomIntGenerator class
                - specify range inclusive in constructor
                - nextValue() method gives you a random integer in range
          - set the color each time we click
             - pick a random integer between 1 and 4
             - if-else statement?
             - keep track of which color we're current using
          - onMouseDrag
             - set the color of the line to the current color we're using
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