AP Java Assignment 11
An ArrayList of Asteroids
Press '4' to rotate left, '5' to accelerate, '6' to rotate right, '2' for hyperspace
You may need to "click" on the applet to give it the "focus"
Background: ArrayList
An array probably isn't the best way to keep track of a buch of asteroids. Arrays have fixed size. You
can't easily add or remove asteroids from an array. A better choice might be an ArrayList. To use an
ArrayList we need to import java.util.ArrayList. The
ArrayList class has a number of useful member methods:
- boolean add(Object x)
- void add(int index, Object element)
- Object get(int index)
- Object remove(int index)
- Object set(int index, Object x)
- int size()
- Iterator iterator()
Steps to completing this assignment
- Create a duplicate of your previous assignment by following steps #1 - 6 again, this time calling your
class ApJava11.java
- Modify your code so that you have an
ArrayList of Asteroids.
- Now we'll modify the applet so that when our space ship strikes an asteroid, the asteroid is removed from the
ArrayList
- Everytime an asteroid moves, we'll compare it's x and y coordinates with the x and y coordinates of the space ship.
- Inside of the loop that moves the asteroids, declare two local variables.
- Store the difference between the x coordinates in one, and the difference between the y coordinates in the other.
- If the absolute value (use
Math.abs) of both differences is less than 20 remove the asteroid from the ArrayList
- Otherwise, move and rotate the asteroid normally
You will need a web page to display your applet. Your homepage should have a link to the web page for this
assignment.
Submit the URL of your applet with the attached Java code (the .java file(s)) in an email message
to mrsimon@lycos.com.