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List Search

List Search. Alice. Common Uses of Lists. Iterating through a list of several like items to accomplish the same task with each item. As in the previous Rockettes example Iterating through a list of several like items to search for one item that has a given property.

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List Search

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  1. List Search Alice

  2. Common Uses of Lists • Iterating through a list of several like items to accomplish the same task with each item. • As in the previous Rockettes example • Iterating through a list of several like items to search for one item that has a given property. • This session demonstrates a list search.

  3. Example • A WacAMole arcade game. • Little moles pop up from holes in the top of the booth. The user tries to whack the mole before it drops out of sight. • The game is over when 10 moles are whacked.

  4. Designing the game • To design the game animation, we need to answer several questions: • How will the game work, overall? • How do we keep score? • How do we know when the user whacks a mole? • How will a list help us?

  5. How will the game work, overall? • A mole pops up and then goes back down. Each time the mole pops up, the user attempts to use the mouse to click the mole. • When a click occurs, we check to see if a mole was clicked. If so, a sound plays and the score increases. • The above actions repeat until the game is over.

  6. Overall design Is the game over? yes congratulate no pop random mole Mouse click event yes Did mouse click on a mole? Play sound Change score display no do nothing

  7. Storyboard for overall game • This is the main driver for the game. • The code will be written in World.my first method • While the game isn't over • randomly select one mole and call popMole • Congratulate the user

  8. Storyboard: popMole popMole Do in order Move the mole up Wait some time Move the mole back down

  9. How do we keep score? • We will use a visual scorekeeper. • The scorekeeper is made up of two cylinders • A gray cylinder above the ground • A yellow cylinder below the ground. • Each cylinder is 1 meter in height.

  10. How do we keep score? • Each time the user successfully clicks a mole, the yellow cylinder will move up 1/10 meter. • When the yellow cylinder is above ground (has moved up 10 times), the game is over.

  11. How do we know when the user has clicked on a mole? • This is where a list comes in handy: • create a list of the moles (one mole is below each hole) • create a mouse click event • each time the mouse is clicked, call a score method to iterate through the list of moles to see whether one of the moles has been clicked!

  12. Storyboard: keep score • Event: User clicks mouse • Response:score • For All in order • If any mole in the mole list was the object clicked • Make a noise • Move the playerscore (yellow cylinder) up 1/10 meter

  13. Demo • Ch09Lec2WacAMole • Concepts illustrated in this example • A item can be randomly selected from a list • In this example, a random mole was popped up from a list of moles. • A visual scorekeeper gives the player feedback on the progress of a game.

  14. Assignment • Read Chapter 9 Section 2, List Search • Read Tips & Techniques 9, Poses

  15. Lab • Chapter 9 Lecture 2 Lab

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