Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Objects Harnessing the Power of Objects Throwing Exceptions

Rafał Stasiak
Rafał Stasiak
3,763 Points

IllegalArgumentException

Hello, Please help me with my code. What is wrong?

GoKart.java
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() {
    drive(1);
  }

  public void drive(int laps) {
    lapsDriven += laps;
    barCount -= laps;
    int numberOfLaps = lapsDriven + laps;
    if (numberOfLaps > MAX_BARS) {
    throw new IllegalArgumentException("Too many laps");
    }
    lapsDriven = numberOfLaps;
  }
}

1 Answer

Steven Parker
Steven Parker
231,269 Points

Here's a few hints:

  • your new code is only to throw the exception, it won't need to make any new changes to "lapsDriven"
  • be sure you test if there aren't enough bars to support the laps request
  • you should not need to create any new variables, just test the ones already there
  • you won't need to reference MAX_BARS for this test
  • make sure you throw the exception before the barCount and lapsDriven fields are changed.