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# Unable to solve!

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() {
mBarsCount = MAX_ENERGY_BARS;
}

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

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

}
```

This method - isFullyCharged() - is used to identify whether a Kart is fully charged or not. It returns [true - if it is fully charged] or [false - if it is not].

We are using isFullyCharged() inside the charge() - method, because we should know the state of the batteries before charge the batteries. And isFullyCharged() gives us the state of the battery -> full or not.

In this case, isFullyCharged() is helper method, but you surely may not use it in your own projects. However, using helper methods is good way to manage your code.

Code:

```public void charge()
{
while(!isFullyCharged())   //while the  batteries are not fully charged
{
mBarsCount++; //charge them
}
}
```

Here: !isFullyCharged() - we are calling this method with the operator (! - "is not"). So, we can read it : while isFullyCharged() is not returning "true" continue charging by incrementing mBarsCount using operator (++ -"increment").

p.s. You can rewrite the code like this if you don't like helper method:

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