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

Chidi Emeh
Chidi Emeh
611 Points

I dont understand the hint "Make sure you throw the exception before change the mBarsCount field". It is not clear enoug

I added a throw if the mBarsCount is becomes less than 0, after adding a laps parameter. I dont understand the question and the hint!!

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;
      if (mBarsCount < 0){
        throw new IllegalArgumentException("Not enough battery remains.");
      }
  }

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

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

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

}

2 Answers

Logan R
Logan R
22,989 Points

You're super close! You need to change two very small things.

First, you'll want to move the if block to be first. You want to check if you have enough before you subtract away.

The second is to change your if statement. Right now, you are checking if mBars is less than 0. This means that it will only throw if you have -1 bars or less. Since 1 bar = 1 lap, you want to check if you have 0 bars or less.

if (mBarsCount < 1){
      throw new IllegalArgumentException("Not enough battery remains.");
}
mBarsCount -= laps;
Chidi Emeh
Chidi Emeh
611 Points

That's true < 1 .... Thanks!!

Logan R
Logan R
22,989 Points

No problem :) If you need any more help, or have any more questions, feel free to ask!