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Java Java Objects Harnessing the Power of Objects Throwing Exceptions

Posted by Artem Prochorov
Artem Prochorov
2,189 Points

Could someone help me to find out what is supposed to be in if statement -->if (*here*)

.

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(int laps) {
    lapsDriven += laps;
    barCount -= laps;
  }
    public void drive() {
    drive(1); 
    if(barCount < 0){
    throw new IllegalArgumentException();
    }
  }
}

2 Answers

Leandro Botella Penalva
Leandro Botella Penalva
17,618 Points
Leandro Botella Penalva
Leandro Botella Penalva
17,618 Points

Hi Artem,

When the program call the method drive it subtracts the equal amount of laps to the barCount. However it is possible that at certain moment you don't have enough bars to perform a lap so you need to control if when a drive method is called you have enough bars (1 per lap) before increasing the lapsDriven counter. If not you need to throw the IllegalArgumentException.

Fahad Mutair
Fahad Mutair
10,359 Points
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;
  }