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Java Java Objects Harnessing the Power of Objects Throwing Exceptions

Kaytlynn Ransom
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Kaytlynn Ransom
Python Web Development Techdegree Student 11,409 Points

Adding logic to the drive method

The exercise is asking me to add logic to the drive method so that it throws an IllegalArgumentException if there aren't enough bars to support the laps request. This is the code that I've got so far. Any ideas as to why it's not working?

GoKart.java
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() {
    drive(1);
    if (laps < 0) {
      throw new IllegalArgumentException("The cart needs at least 1 bar of energy to run a lap.");
  }

  public void drive(int laps) {
    lapsDriven += laps;
    barCount -= laps;
  }
 }
}

2 Answers

Fahad Mutair
Fahad Mutair
10,359 Points

He is asking you to fix the error in the drive method that accepts laps which is

public void drive(int laps)

the error here you can do more laps lapsDriven than your battery barCount and each lap will consume 1 energy bar, so logically you can't do laps without energy. so you have to add if statement to check if there is enough energy to preform this many laps or not.

if (laps > barCount)

if not throw exception.

throw new IllegalArgumentException("there aren't enough bars to support the laps requested!");

this is the final code

public void drive(int laps) {
    if (laps > barCount){
         throw new IllegalArgumentException("there aren't enough bars to support the laps requested!");
   }
    lapsDriven += laps;
    barCount -= laps;
  }

The check to determine if the number of laps exceeds the current barCount should occur in the drive method which accepts the number of laps as an argument.

 public void drive(int laps) {
    if (laps > barCount) {
         throw new IllegalArguementException();
    }
    lapsDriven += laps;
    barCount -= laps;
  }