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

cherishli
cherishli
654 Points

Please help with Java question. " Add logic to the drive method so that it throws an IllegalArgumentException...

I have been stuck on this for absolutely ages, I can't see the error. I am very confused. Any help would be greatly appreciated.

The question is: You probably already spotted the error in the drive method that accepts laps. You can drive way more laps than our battery can handle. Let's fix it.

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.

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) {
    if (lapsDriven > barCount)
      throw new IllegalArgumentException ("Not enough energy in bars!");
  } else {
   lapsDriven += laps;
    barCount -= laps;
  }
}
cherishli
cherishli
654 Points

I have managed to get it to this:

public void drive(int laps) { if (laps <= barCount); lapsDriven += laps; barCount -= laps;
} else; { throw new IllegalArgumentException("Not enough energy in bars!"); } }

The preview says: ./GoKart.java:34: error: illegal start of type } else; { ^ 1 error

1 Answer

cherishli
cherishli
654 Points

Ok for anyone who stumbles across this I have got the answer, looking at the bottom part only:

public void drive (int laps){ if (laps > barCount) { throw new IllegalArgumentException("Not enough energy in bars!"); } lapsDriven += laps; barCount -= laps; }

I hope this works for you.