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Java Java Objects (Retired) Harnessing the Power of Objects Method Signatures

Posted by ahmed alghafli
ahmed alghafli
3,446 Points

have added a method drive that defines a parameter laps. These high-powered GoKarts use 1 energy bar off their battery

what should I do

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

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

  public String getColor() {
    return mColor;
  }

  public void drive(int laps) {
    // Other driving code omitted for clarity purposes
    mBarsCount -= laps;
  }

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

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

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

}
ahmed alghafli
ahmed alghafli
3,446 Points

have added a method drive that defines a parameter laps. These high-powered GoKarts use 1 energy bar off their battery per lap. Using method signatures, add a new default method called drive that performs just 1 lap and takes no arguments. this is the question

3 Answers

Clayton Perszyk
MOD
Clayton Perszyk
Treehouse Moderator 48,735 Points
Clayton Perszyk
Clayton Perszyk
Treehouse Moderator 48,735 Points

create another drive method like this: 

public void drive() {

}

You'll notice there are no arguments for this drive method; after adding this method you will have two drive methods in your GoKart class, but they have different signatures (in this case one method takes an argument and the other doesn't), so they won't be in conflict with one another.

Inside the new drive method you want to call the original drive method and pass it an int value of 1:

drive(1);

Combine those two snippets together and the code should pass.

Mahdi Darwish
Mahdi Darwish
945 Points
Mahdi Darwish
Mahdi Darwish
945 Points

Works great! Thanks

Augusto Hernandes
Augusto Hernandes
1,818 Points

I still don't understand :(

Clayton Perszyk
MOD
Clayton Perszyk
Treehouse Moderator 48,735 Points
Clayton Perszyk
Clayton Perszyk
Treehouse Moderator 48,735 Points

You want to create another public void function named drive that doesn't take any arguments; within that function you call the original drive method, passing in the number 1 as the argument for laps. Because the new function has a different method signature, it won't conflict with the original function. Here's a link to the wikipedia page for method signatures: http://en.wikipedia.org/wiki/Type_signature#Method_signature

ahmed alghafli
ahmed alghafli
3,446 Points
ahmed alghafli
ahmed alghafli
3,446 Points

I am still confused

John Weland
John Weland
42,478 Points

ahmed alghafli what is happening here in this answer above is

there is an existing method called drive that takes in an int called laps, and for every lap it decrements the mBarsCount by 1.

then you have to create a new method called drive that takes in to parameters, that method drive that you created calls the existing method drive by the number you pass into it like so. 

//existing method
public void drive(int laps) {
    mBarsCount -= laps;  //decrement mBarsCount 1 time for each laps
}

// New method you create
public void drive() {
    drive(1); // this calls the existing drive method where 1 is the number of laps
}