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

Willie Suggs
PLUS
Willie Suggs
Courses Plus Student 5,879 Points
Posted by Willie Suggs
Willie Suggs
Courses Plus Student 5,879 Points

any understanding you can give would be nice!

i follow along in videos, i take notes, i copy the code straight from the video but once i try to apply it, it seem like i can't figure the correct why to write it. Not only do i need help with this current issue, but i need advise on what am i losing from the video to my exercise & what do you advise me to do to get better beyond what I'm already doing...thanks from the rookie :)

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);
    if (drive() > mBarsCount) {
      throw new IllegalArgumentException("Not enough battery remains");
   }
  }

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

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

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

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

}

1 Answer

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

You have drive calling itself, which will result in an infinite recursion. Because you have two drive methods and the drive() with no arguments calls the drive(int) method straight away, the exception throwing code should go in the drive(int methmBarsod). Then in the drive(int) method, you need to check if laps is greater than mBarsCount and throw the exception.

Willie Suggs
Willie Suggs
Courses Plus Student 5,879 Points
Willie Suggs
Willie Suggs
Courses Plus Student 5,879 Points

public drive (int laps) { mBarsCount -= laps; if (mBarsCount < laps) { throw new IllegalArgumentException("not enough battery remains); }

what am i doing wrong?

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

When you're checking to see if there'll be a problem, it's better to check before the problem than after it. Here the problem is deducting more battery charge than is available, so you need to check the amount of battery before you deduct it not after.