a function to charge a battery until it is fully charged and the function return it is fully charged

Hi Daniel,

The isFullyCharged method is a helper method designed to give you quick access to the GoKart's charge state. It returns true or false, as you would expect. It does not charge the GoKart instance. That's what the charge() method does for you.

So, you use the isFullyCharged() method to see if your GoKart instance needs to use the charge method.

Let's look at the question as this gives us lots of hints how to tackle this one:

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.

That's quite a lot ... what it is saying is: In the charge method, while the GoKart not isFullyCharged() do mBarsCount++. That's not very readable! Let's do that in code:

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

And that's it. We modify the charge() method. First, we enter a while loop. This loops constantly while the condition !isFullyCharged() is true. So it loops while the GoKart isn't fully charged. Inside the loop, it increments the mBarsCount variable. On the next loop, it checks isFullyCharged() again, if it isn't fully, charged, the loop runs, if it is fully charged, the method exits.

Make sense?

Steve.