Java Java Objects Harnessing the Power of Objects Overload Methods

Kendhall Lebron Ruiz
Kendhall Lebron Ruiz
Pro Student 1,143 Points

I don't understand the drive method

It's asking "Modify the drive method to define a parameter of how many laps should be driven. Update the method body to handle the new parameter." I know I have to use the += and -= thing but I don't know how to use them here. I already got the right answer but I guessed it. An explanation would be appreciated.
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() {

1 Answer

Steven Parker
Steven Parker
195,597 Points

You say that you "got the right answer", but it's not shown here. This is the code the challenge starts with.

But to explain the "+= and -= thing", those are the increment and decrement operators. Both of them change the value of the term on the left by the amount represented on the right. So "dogs += 3" would raise the count of "dogs" by 3, and "students -= seniors" would decrease the current student count by the number of folks who are graduating (the senior class).