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 (Retired) Harnessing the Power of Objects Throwing Exceptions

Matthew Denton
Matthew Denton
598 Points
Posted by Matthew Denton
Matthew Denton
598 Points

How do I add an illegalArgumentException from the drive method if the requested number of laps cannot be completed

I'm getting no compiler error message but I'm gettin this error message - Bummer! Are you sure you threw the IllegalArgumentException if the requested amount of laps would make the battery less than zero?

Can someone please advise?

GoKart.java 
public class GoKart {
  public static final int MAX_BARS = 8;
  private String mColor;
  private int mBarsCount;

  public GoKart(String color) {
    mColor = color;
    mBarsCount = 0;
  }

  public String getColor() {
    return mColor;
  }

  public void drive() {
    drive(1);
   if(laps < mBarsCount)
      throw new IllegalArgumentException("Not Enough Battery Remains");
  }

  public void drive(int laps) {
    // Other driving code omitted for clarity purposes
    mBarsCount -= laps;
  }

  public void charge() {
    while (!isFullyCharged()) {
      mBarsCount++;
    }
  }

  public boolean isBatteryEmpty() {
    return mBarsCount == 0;
  }

  public boolean isFullyCharged() {
    return mBarsCount == MAX_BARS;
  }

}

3 Answers

Rebecca Bompiani
Rebecca Bompiani
16,996 Points
Rebecca Bompiani
Rebecca Bompiani
16,996 Points

Hi Matthew-

You're so close! You'll want to add your code to the the method below the one you're currently using. Because the method you've chosen takes no input parameter (no laps), it has nothing to compare in your if statement. Also, don't forget the curly braces in your if statement!

Try this:

  public void drive(int laps) {
    // Other driving code omitted for clarity purposes
    if (mBarsCount < laps){
      throw new IllegalArgumentException("Not enough battery remains");
    }
    mBarsCount -= laps;
  }
Marileen Mennerich
Marileen Mennerich
1,161 Points
Marileen Mennerich
Marileen Mennerich
1,161 Points

You put your exception into the wrong drive()-method. Use the one that accepts an argument "laps", then check whether laps > mBarsCount before the line that reduces the mBarsCount. (Note, that's a "greater than", your code currently has a "less than", so don't just copy it over.)

Jess Sanders
Jess Sanders
12,086 Points
Jess Sanders
Jess Sanders
12,086 Points 
  public void load(int pezAmount) {
    int newAmount = mPezCount + pezAmount;
    if (newAmount > MAX_PEZ) {
      throw new IllegalArgumentException("Too many pez!");
    }
  }

Follow the above example to modify the drive method that takes an argument (int laps).