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Nicholas Anstis
2,095 PointsJava Challange getting this error "cannot assign a value to final variable"
Here's my code and for some reason the "final" keyword mess up something.
public class GoKart {
public static final int MAX = 8;
private String mColor;
public final int mGoKart;
public GoKart(String color) {
mColor = color;
}
public void load() {
mGoKart = MAX;
}
public String getColor() {
return mColor;
}
}
5 Answers
Steve Hunter
57,712 PointsHi Nicholas,
Let's walk through the challenge. First, Let's add a constant field to the class that stores the maximum number of energy bars. You've done this right with your line:
public static final int MAX = 8;
Next, Now let's add a private uninitialized field to store the current number of energy bars. Name it mBarsCount. Initialize it to zero in the constructor. So, we need to create a new member variable with a given name. It holds an integer and is private. We set it to zero in the constructor. So, at the top of the class:
public class GoKart {
private String mColor;
public static final int MAX = 8;
private int mBarsCount; // added here
Then, in the constructor:
public GoKart(String color) {
mColor = color;
mBarsCount = 0; // added this line
}
The, lastly, let's add a method named charge. It should be public and return nothing. When called it should set mBarsCount to the value of the constant you declared in Task 1. So, we need a new method that sets mBarsCount to MAX. It is public, returns nothings, takes no parameters and is called charge:
// whole new method
public void charge(){
mBarsCount = MAX;
}
And that's it!
I hope that helps,
Steve.
Jeremy Hill
29,567 PointsThis line you have might be what is causing your problem:
public final int mGoKart;
There shouldn't be a final there, or an int:
public GoKart(String color){
}
Julian Garcia
18,380 Pointsfinal keyword is used for constants, where they are defined they need to assign a value and it cannot be changed later.
So try changing to this:
private int mBarsCount; //They ask to be a private variable
instead
public final int mGoKart; // what's this for, Julian?
the function you name load , they ask to name it charge, so just change the name.
They also ask to initialize the variable mBarsCount to zero in constructor, GoKart method and add
public GoKart(String color) {
mColor = color;
//Here assign zero to mBarsCount
}
Hope this help.
Jeremy Hill
29,567 PointsYour final declaration should look like this:
public static final int MAX_BARS = 8;
Nicholas Anstis
2,095 PointsOh I get it. Thanks a lot
Nicholas Anstis
2,095 PointsActuall it doesn't work. Changing it doesn't do anything.
And the error is in the public final int mGoKart;
Steve Hunter
57,712 PointsYou also need to remove the line:
public final int mGoKart;
That's the final that is causing the problem as you are later trying to assign to that variable in your load method where you set mGoKart = MAX. You can't assign to a final variable except on the same line you declare it.
So, public final int mGoKart = MAX; is fine (but not the solution), but assigning to mGoKart later isn't allowed.
I've written a walk-through of the challenge step-by-step. I hope that helps.
Nicholas Anstis
2,095 PointsThanks you all of you. I got this right :]