Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Java Java Objects Harnessing the Power of Objects Throwing Exceptions

Kevin Jervis
Kevin Jervis
884 Points

Not too sure what I've done wrong here. Code is not compiling.

Task Description: "Add logic to the drive method so that it throws an IllegalArgumentException if there aren't enough bars to support the laps request. Remember it takes 1 bar of energy to go around a lap."

class GoKart {
  public static final int MAX_BARS = 8;
  private String color;
  private int barCount;
  private int lapsDriven;

  public GoKart(String color) {
    this.color = color;

  public String getColor() {
    return color;
  public void charge() {
    barCount = MAX_BARS;

  public boolean isBatteryEmpty() {
    return barCount == 0;

  public boolean isFullyCharged() {
    return MAX_BARS == barCount;

  public void drive() {

  public void drive(int laps){
    lapsDriven += laps;
    barCount -= laps;
  if (laps - MAX_BARS < 0){
      throw new IllegalArgumentException 
      ("lapsset are more than the capacity of the battery");

1 Answer

Cam Richardson
Cam Richardson
Front End Web Development Treehouse Moderator 16,894 Points

Hello Kevin!

It looks like your if statement is not inside your drive method and is actually sitting on its own inside your class. That's what is causing the compiler error.

Hope that helps!

Kevin Jervis
Kevin Jervis
884 Points

Hi Cam

That's brilliant. Thanks for your help :)