I'm stuck again. What am I missing?

Question

GoKart.java

public class GoKart {
  public static final int MAX_BARS = 8;
  private String mColor;
  private int mBarsCount;

  public GoKart(String color) {
    mColor = color;
    mBarsCount = 0;
  }

  public String getColor() {
    return mColor;
  }
  public void drive() {
    drive(MAX_BARS);
  }

  public void drive(int laps) {
    mBarsCount -= laps;
    drive(1);
  }

  public void charge() {
    while (!isFullyCharged()) {
      mBarsCount++;
    }
  }

  public boolean isBatteryEmpty() {
    return mBarsCount == 0;
  }

  public boolean isFullyCharged() {
    return mBarsCount == MAX_BARS;
  }

}

Answer 1 · 2015-01-14T20:53:32Z

January 14, 2015 8:53pm

Hi,

Not sure what is your issue, but this code:

 public void drive() {
    drive(MAX_BARS);
  }

  public void drive(int laps) {
    mBarsCount -= laps;
    drive(1);
  }

can cause stack overflow, because you are recursively invoking the drive(1) method and you don't have a stop condition. So if you invoke drive(), whicl will invoke drive(8), then mBarsCount -= 8 will be executed and the drive(1) method is invoked AGAIN, it enters in drive(int laps) method, executes mBarsCount -= 1 at this moment mBarsCount has value -9 AND invokes drive(1) AGAIN and in the next step you will have mBarsCount value -10 and so on. I don't know exactly what you want to implement, but I suppose you need to stop, lets say when the mBarsCount will be less or equal to 0 (mBarsCount <= 0):

 public void drive(int laps) {
   mBarsCount -= laps;
   if (mBarsCount <= 0) {
     return; 
   } else {  
     drive(1);
   }
  }

Answer 2 · 2015-01-14T20:54:45Z

January 14, 2015 8:54pm

HINT: Using method signatures, add a new default method called drive that performs just 1 lap and takes no arguments.

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Joe Steffy

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I'm stuck again. What am I missing?

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