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

Jay Bhatt
Jay Bhatt
6,502 Points
Posted by Jay Bhatt
Jay Bhatt
6,502 Points

How do I use the IllegalArgumentMethod to eliminate someone inputting laps that make the battery less than 0?

I have the code right here and I believe the condition of the laps having to be greater than 0 eliminates that problem. However, it is not accepting it. please help.

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();
  }

  public void drive(int laps) {
    int lapRemain = mBarsCount + laps;
    int lapsRemain= Math.abs(lapRemain);
    if (lapsRemain > MAX_BARS && laps > 0) {
      throw new IllegalArgumentException("Not enough battery remain");
    }
    mBarsCount = lapsRemain;
  }

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

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

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

}
Jeremy Hill
Jeremy Hill
29,567 Points

The variable that you created "lapRemain" you set it equal to the laps + mBarsCount. You need to remove the number passed in from the mBarsCount; like this: mBarsCount -= laps; This is a short cut to saying: mBarsCount = mBarsCount - laps; So each lap driven will be removed from the battery until the battery returns empty. If someone tries to drive further than the battery will allow an exception will be thrown alerting the user that they can't go that many laps.

2 Answers

Kristian Gausel
Kristian Gausel
14,661 Points
Kristian Gausel
Kristian Gausel
14,661 Points 
  public void drive(int laps) {
    if (laps > mBarsCount || laps < 0) {
      throw new IllegalArgumentException("Not enough battery remain");
    }
    mBarsCount -= laps;
  }

No need to make it complicated

Kristian Gausel
Kristian Gausel
14,661 Points
Kristian Gausel
Kristian Gausel
14,661 Points

Although you don't really need the "or laps < 0" part

Jay Bhatt
Jay Bhatt
6,502 Points
Jay Bhatt
Jay Bhatt
6,502 Points

I went with just doing I have not tried your but I am sure it works public void drive(int laps) { int LapRemain = mBarsCount- laps; if (LapRemain < mBarsCount) { throw new IllegalArgumentException("Not enough battery"); } }

Kristian Gausel
Kristian Gausel
14,661 Points
Kristian Gausel
Kristian Gausel
14,661 Points

Just a tip: learn to not write complicated code for simple problems.

Jeremy Hill
Jeremy Hill
29,567 Points
Jeremy Hill
Jeremy Hill
29,567 Points

For this challenge it is not really necessary to create another variable. All you really need to do is check whether the argument (laps) is more than the remaining battery (mBarsCount) if it is throw the exception if it is not then decrease the mBarsCount variable by the number that was passed in.

Jay Bhatt
Jay Bhatt
6,502 Points
Jay Bhatt
Jay Bhatt
6,502 Points

I saw your comment (the earlier one), it really helped, I was not thinking straight with that yesterday.

Here is what I did

public void drive(int laps) { int LapRemain = mBarsCount- laps; if (LapRemain < mBarsCount) { throw new IllegalArgumentException("Not enough battery"); } }