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Java Java Objects Harnessing the Power of Objects Throwing Exceptions

David Dooley
David Dooley
3,028 Points

Don't understand the question.

Add logic to the drive method so that it throws an IllegalArgumentException if there aren't enough bars to support the laps request. Remember it takes 1 bar of energy to go around a lap.

class GoKart {
  public static final int MAX_BARS = 8;
  private String color;
  private int barCount;
  private int lapsDriven;

  public GoKart(String color) {
    this.color = color;

  public String getColor() {
    return color;
  public void charge() {
    barCount = MAX_BARS;

  public boolean isBatteryEmpty() {
    return barCount == 0;

  public boolean isFullyCharged() {
    return MAX_BARS == barCount;

  public void drive() {

  public void drive(int laps) {
   int newAmount = laps;
    if(newAmount <  ){
    throw new IllegalArgumentException("Too many bars");

2 Answers

28,538 Points

You have to compare the amount of laps that is requested against the current battery bar count which is stored in the barCount variable. Your current code is not too far of from correct, though I'd like to point out that the newAmount variable you have created is entirely pointless as it is just a copy of the laps variable that already exists within the method.

So to summarize compare barCount against laps. If the requested amount of laps is higher than the bars stored in the battery (barCount) then you should throw the exception.