Im so confused

Let me clarify. I was saying to throw an iae if (mBarsCount<laps). Please see comments:

  public void drive(int laps) {
    //If number of battery bars is less than the number of laps, throw an iae
    if(mBarsCount < laps){
      throw new IllegalArgumentException("Not enough battery remains.");  
    }
    // run the GoKart and deplete the battery for the number of laps.
    mBarsCount -= laps;
  }

Background information:

• mBarsCount is the battery remaining in the GoKart. (Maximum 8 bars)
• laps is the number of laps the GoKart is needed to run.
• assuming 1 lap will need 1 bar of battery. It is needed to prevent the GoKart from running more laps than it can handle. (mBarsCount should be more or equal to laps)

So before driving (mBarsCount -= laps), you need to throw the IllegalArgumentException if (mBarsCount < laps).

I'm now getting "Bummer! Are you sure you threw the IllegalArgumentException if the requested amount of laps would make the battery less than zero?" 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(MAX_BARS); }

public void drive(int laps) { // Other driving code omitted for clarity purposes mBarsCount -= laps; int newDriveAmount = mBarsCount + laps; if (mBarsCount >= laps) { throw new IllegalArgumentException("Not enough battery remains"); } mBarsCount = newDriveAmount; }

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

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

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

}

Ok thanks for that.

1. You don't need int newDriveAmount = mBarsCount + laps;, and
2. if (mBarsCount >= laps) { should be if (laps > mBarsCount) {.