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Java Java Objects (Retired) Harnessing the Power of Objects Throwing Exceptions

Aldrich Alviar
Aldrich Alviar
2,745 Points

Illegal argument exception

how to code throwing IllegalArgumentException "Not enough battery remains"

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(1);
  }

  public void drive(int laps) {
    // Other driving code omitted for clarity purposes
    mBarsCount -= laps;
  }

  public void drive(int lapsNumber) {
    if (lapsNumber < MAX_BARS) {
      throw new IllegalArgumentException ("Not enough battery remains");
    }
    mBarsCount = lapsNumber;
  }

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

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

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

}

1 Answer

J.D. Sandifer
J.D. Sandifer
18,813 Points

You're definitely on the right track here. In fact, it look likes there are just a few simple errors related to following the directions more closely and thinking about what you're trying to accomplish - the main exception throwing code looks good!

Checkout my hints for the drive(int lapsNumber) method:

public void drive(int lapsNumber) {
    if (lapsNumber < MAX_BARS) {        // the goal here is to check if we're trying to drive *more* laps than battery
      throw new IllegalArgumentException ("Not enough battery remains");     // check directions: the message needs punctuation, right?
    }
    mBarsCount = lapsNumber;  // this should decrease the bars by the number of laps (leave it as it originally was "-=")
  }