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Java Java Objects (Retired) Harnessing the Power of Objects Incrementing

Posted by Matthew Earlywine
Matthew Earlywine
2,560 Points

While loop

I thought I found the answer to this question, but I still got an error message.

Okay, so let's use our new isFullyCharged helper method to change our implementation details of the charge method. Let's make it so it will only charge until the battery reports being fully charged. Let's use the ! symbol and a while loop. Inside the loop increment mBarsCount.

GoKart.java 
public class GoKart {
  public static final int MAX_ENERGY_BARS = 8;
  private String mColor;
  private int mBarsCount;

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

  public String getColor() {
    return mColor;
  }

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

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

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

}
Alex Brown
Alex Brown
3,555 Points

What error message was it? That would help with finding the solution.

3 Answers

Dennis Mårtensson
Dennis Mårtensson
7,400 Points
Dennis Mårtensson
Dennis Mårtensson
7,400 Points

Ah. There's a typo. It should be "while (! isFullyCharged())". Forgot the "d" at the end of "isFullyCharged()", and you also had a semicolon that shouldn't be there!

Matthew Earlywine
Matthew Earlywine
2,560 Points

I changed it to while (! isFullyCharged()) but I still got an error message

Bummer! Use ++ to increment the mBarsCount member field.

Jonathan Walker
Jonathan Walker
1,984 Points
Jonathan Walker
Jonathan Walker
1,984 Points

public void charge() { while (! isFullyCharge()); { mBarsCount ++;

Should be "isFullyCharged"

Also, should not be a space between "!" and "isFullyCharged".

Dennis Mårtensson
Dennis Mårtensson
7,400 Points
Dennis Mårtensson
Dennis Mårtensson
7,400 Points

Actually, the space between "!" and "isFullyCharged()" is legal, the compiler ignores whitespace. Although it looks a tad bit off, it will still compile!

Matthew Earlywine
Matthew Earlywine
2,560 Points
Matthew Earlywine
Matthew Earlywine
2,560 Points

Thanks for all your help! I didn't think a space between ! Fullycharged and mBarsCount ++ mattered. Why does the space matter though?