I am failing to get through this challenge where i have to use the while loop and the symbol !.

Hi Ashford,

Let's break down the instructions and figure out what we need to do.

let's use our new isFullyCharged helper method to change our implementation details of the charge method

This tells us we'll be using isFullyCharged insdie the charge method. Here's the charge method given to us:

public void charge() {
  mBarsCount = MAX_ENERGY_BARS;
}

Currently, charge will set mBarsCount equal to 8. However, the challenge is asking us to change this method so "it will only charge until the battery reports being fully charged."

We're also told to "use the ! symbol..." (which toggles boolean values) "...and a while loop. Inside the loop increment mBarsCount."

Let's start by adding a while loop to the charge method.

public void charge() {
  while () {
    mBarsCount = MAX_ENERGY_BARS;
  }
}

Recall that isFullyCharged will return a boolean value. It returns true if mBarsCount equals 8 or false otherwise. We can use this as the while's conditional.

public void charge() {
  while (isFullyCharged()) {
    mBarsCount = MAX_ENERGY_BARS;
  }
}

This still doesn't seem quite right. We want this loop to run while mBarsCount is not fully charged. That's where the ! symbol comes in.

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

OK, now the loop conditional is setup correctly, but we still have one more problem to solve. Inside the loop, instead of setting it to MAX_ENERGY_BARS for each loop iteration, we need to increment mBarsCount by 1 for each loop iteration.

I'll let you try and figure that part out. If you're still having trouble, please leave a comment and I'll explain how to increment a variable.

Cheers