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

Avery Freeman-wheaton
Avery Freeman-wheaton
2,273 Points
Posted by Avery Freeman-wheaton
Avery Freeman-wheaton
2,273 Points

Trouble with throw new IllegalArgumentException in GoKart exercise

Hi,

I seem to be having trouble now with the 

throw new IllegalArgumentException("Not enough battery remains");

Here's my codeblock I tried, but can't get to work:

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

Not really sure how to do this. I tried to put it in as similarly as the demonstration showed, but I just don't seem to be able to get it.

Thanks! -Avery

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(int laps) {
    // Other driving code omitted for clarity purposes
    mBarsCount -= laps;
    int newLapsLeft = mBarsCount - laps;
    if (newLapsLeft > MAX_BARS) {
     throw new IllegalArgumentException("Not enough battery remains");
    }
    mBarsAmount = newLapsLeft;
  }

   public void drive() {
    drive(1); 
  }



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

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

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

}

1 Answer

Gene Osborne
Gene Osborne
8,630 Points

Take notice of these two lines of code:

mBarsCount -= laps;
int newLapsLeft = mBarsCount - laps;

You are substracting the laps twice!

That being said, you are overthinking it. All you need to do is check if it can be done:

public void drive(int laps) {
    // Other driving code omitted for clarity purposes
    if(mBarsCount <= laps) throw new IllegalArgumentException("Not enough battery remains");
    else mBarsCount -= laps;
  }
Avery Freeman-wheaton
Avery Freeman-wheaton
2,273 Points
Avery Freeman-wheaton
Avery Freeman-wheaton
2,273 Points

Thank you! That really helped!

I really appreciate the help in these forums. Sorry it took me so long to reply. Have a nice day!