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Java Java Objects (Retired) Harnessing the Power of Objects Throwing Exceptions

Jennifer Bird
Jennifer Bird
4,287 Points
Posted by Jennifer Bird
Jennifer Bird
4,287 Points

Part 1 of Exception challenge . Did anyone find the answer? How do I throw and Illegal Exception on drive?

I took a 2 day pause before doing this code now I got really confused... Do I write a code on drive method that is something like "if (mBarsCount = isBattery Empty) { throw new IllegalArgumentException ("not enough battery?") ?

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);

  }

  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;
  }

}

2 Answers

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Jennifer,

You're on the right lines, yes. You test the outcome, throwing an exception if the condition is met. It could look something like the below, but there are other solutions that work just as well:

  public void drive(int laps) {
    // Other driving code omitted for clarity purposes
    if(mBarsCount - laps < 0) {
      throw new IllegalArgumentException("Not enough battery remains");
    } else {
      mBarsCount -= laps;
    }
  }

I hope that helps.

Steve.

Steve Hunter
Steve Hunter
57,712 Points

For example, a neater test could be:

if(mBarsCount < laps) {
.
.
.
}
Terence Evans
Terence Evans
1,870 Points

When I compile this I get " unreachable statement mBarsCount -= laps; ^ Everything I've entered appears to be correct and as shown. mBarsCount was initialized in the 4th line. Ie. "private int mBarsCount;" Any idea why I'm getting this compiler message?

Steve Hunter
Steve Hunter
57,712 Points

Hi Terence,

Can you paste your code in here, please? We should be able to get it fixed quickly.

Steve.

Jennifer Bird
Jennifer Bird
4,287 Points
Jennifer Bird
Jennifer Bird
4,287 Points

Hey that helped a lot. Thanks!