# COMP1110 Lab 5
## Before the Lab
* Complete week 6 of your personal journal, commit and push at least 5 minutes prior to your lab.
* Make sure you’ve covered the modules [**J9**](https://cs.anu.edu.au/courses/comp1110/lectures/java/#J9) (Lambda expressions) and [**X1**](https://cs.anu.edu.au/courses/comp1110/lectures/javafx/#X1) (JavaFX)
## Purpose
In this lab you will write a simple Java FX program.
**It is essential that you complete this lab and have a tutor mark it off during the lab**.
## A simple JavaFX animation
Your objective here is to familiarize yourself further with JavaFX by creating
a simple window with a moving ‘ant’.
In the Java package comp1110.lab5, within your comp1110-labs
repository, create a new Java class, `Ant`, that draws the path of an
ant that is walking randomly around a JavaFX window. This should look
a little like a scribbling on a page. If the ant walks off the edge of
the screen re-center the ant and continue the random walk. Use the
basic template from the code from lecture X01 (or the
[HelloTutor](../lab1/HelloTutor.java) example from Lab 1). In addition
to that, you may find the following helpful:
““java
…
primaryStage.setScene(scene);
Timeline timeline = new Timeline(new KeyFrame(Duration.millis(100),
ae -> {
/* your code goes here */
}));
timeline.setCycleCount(Animation.INDEFINITE);
timeline.play();
primaryStage.show();
…
““
that little bit of code will be called once every 100 milliseconds (10 times a second).
## Extension
**Use recursion to reverse an ArrayList**
Create a recursive method reverseArray.
The method should take an ArrayList of characters and return the same ArrayList with the characters reversed.
E.g. if you start with `[‘a’,’b’,’c’,’d’,’e’]` the method should return `[‘e’,’d’,’c’,’b’,’a’].
For the method to be recursive, it needs to call itself at some point.
**Use recursion to print a triangle (harder)**
Create a method `trianglePrinter`.
The method should take an integer as input, and print out a triangle with that many rows.The triangle should look like the triangle from lab 2, except the bottom row should have spaces instead of stars.
For example, if you run trianglePrinter(5):
“`
____*
___*_*
__*___*
_*_____*
*_______*
“`
To be recursive, the method needs to call itself at some point.