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Java Java Objects Harnessing the Power of Objects Throwing Exceptions

Posted by Roger sam
Roger sam
575 Points

code/logic is not working.

You probably already spotted the error in the drive method that accepts laps. You can drive way more laps than our battery can handle. Let's fix it.

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() { drive(1); } public void drive(int laps) { int newLaps = lapsDriven + laps; if (newLaps > MAX_BARS) { throw new IllegalArgumentException (“too many laps”); }
newLaps = lapsDriven; barCount -= laps; }

}

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);
  }

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

  public void drive(int laps) {
    int newLaps = lapsDriven + laps;
      if (newLaps > MAX_BARS) {
           throw new IllegalArgumentException (“too many laps”);
          }    
   newLaps = lapsDriven;
  }

}

2 Answers

John McGarvey
John McGarvey
14,026 Points
John McGarvey
John McGarvey
14,026 Points

You have two public void drive(int laps) methods within the same class. You can only have one. I would not think this would compile, but if it does, only the first will be called. You have newLaps = lapsDriven in the second one, when what you want is lapsDriven = newLaps. The second one also is not subtracting from the barCount, when it should.

Roger sam
Roger sam
575 Points

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); }

public void drive(int laps) { int newLaps = lapsDriven + laps; if (newLaps > MAX_BARS) { throw new IllegalArgumentException (“too many laps”); }
lapsDriven = newLaps; barCount -= laps ; }

}

//followed your suggestion.still did not work. substracted the barCount with ( barCount -= laps and barCount --) separately but still did not work.

need assistance thanks.

John McGarvey
John McGarvey
14,026 Points
John McGarvey
John McGarvey
14,026 Points

I am not sure why it is not working now, but one possible reason is that the GoKart could be charged again after some laps are driven, or, someone could attempt to drive the GoKart before charging. Instead of if (newLaps > MAX_BARS) you probably want if (laps > barCount) .