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

Posted by lee lewis
lee lewis
Courses Plus Student 5,796 Points

dont understand "bummer" comment

it sais "make sure you throw the exception before you change the mBarCount field"

i dont understand this

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;
    if (mBarsCount < 1) {
      throw new IllegalArgumentException("Not enough battery remains");
    }
  }

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

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

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

}

2 Answers

Sonya Trachsel
Sonya Trachsel
13,674 Points
Sonya Trachsel
Sonya Trachsel
13,674 Points

instead of

public void drive(int laps) { // Other driving code omitted for clarity purposes mBarsCount -= laps; if (mBarsCount < 1) { throw new IllegalArgumentException("Not enough battery remains"); } }

try this -----

public void drive(int laps) { // Other driving code omitted for clarity purposes if(laps > mBarsCount) { throw new IllegalArgumentException("Not enough battery remains"); } mBarsCount -= laps;

Sonya Trachsel
Sonya Trachsel
13,674 Points
Sonya Trachsel
Sonya Trachsel
13,674 Points

Sorry, I found the mistake. This should be right:

public void drive(int laps) { // Other driving code omitted for clarity purposes if(laps > mBarsCount) { throw new IllegalArgumentException("Not enough battery remains"); } mBarsCount -= laps; int enoughCharge = mBarsCount -= laps; }

You need to move the if block to be first. Hope this helps!