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Java Java Objects Harnessing the Power of Objects Increment and Decrement

Posted by Dominic Cruz-Pena
Dominic Cruz-Pena
546 Points

First, create a new private int field named lapsDriven.

I cant get it hen i try public void drive(){ lapsDriven++; }

GoKart.java 
class GoKart {
  public static final int MAX_BARS = 8;
  private String color;
  private int barCount;

  public GoKart(String color) {
    this.color = color;
  }

  public String getColor() {
    return color;
  }

  public void charge() {
    barCount = MAX_BARS;
  }

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

  public boolean isFullyCharged() {
    return MAX_BARS == barCount;
  }
}
Muhammad Asif
Muhammad Asif
Courses Plus Student 557 Points
Muhammad Asif
Muhammad Asif
Courses Plus Student 557 Points 
class GoKart {
  public static final int MAX_BARS = 8;
  private String color;
  private int barCount;
  private int lapsDriven;

  public GoKart(String color) {
    this.color = color;
  }

  public String getColor() {
    return color;
  }

  public void charge() {
    barCount = MAX_BARS;
  }

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

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

[MOD: edited this code block too -srh]

5 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi Dominic,

You are creating a new member variable, not a method.

So, you want a private variable called lapsDriven that's an int. Try: 

private int lapsDriven;

Put that at the top of the class with the other member variables.

I hope that helps,

Steve.

Joseph Wasden
Joseph Wasden
20,407 Points
Joseph Wasden
Joseph Wasden
20,407 Points

Your code worked fine for me. Make sure you have declared the variable, perhaps?

class GoKart {
  public static final int MAX_BARS = 8;
  private String color;
  private int barCount;
  private int lapsDriven; //<-- make sure this variable is declared as shown

  public GoKart(String color) {
    this.color = color;
  }

  public void drive() { // this is your code that you provided with this question
    lapsDriven++; 
  }
Nourez Rawji
Nourez Rawji
3,303 Points
Nourez Rawji
Nourez Rawji
3,303 Points

Did you remember to add the private int lapsDriven; at the top of the class? You can't increment a variable before you declare it.

Steve Hunter
Steve Hunter
57,712 Points

My apologies! I saw your topic showing that you're at the start of the challenge where you define the lapsDriven member variable. The second piece of the challenge requires the drive() method to be created.

If you're at the second part, your method is correct as long as you have declared the member variable as in my first answer. Nourez called that right.

Steve.

Muhammad Asif
PLUS
Muhammad Asif
Courses Plus Student 557 Points
Muhammad Asif
Muhammad Asif
Courses Plus Student 557 Points 
class GoKart {
  public static final int MAX_BARS = 8;
  private String color;
  private int barCount;
  private int lapsDriven;

  public GoKart(String color) {
    this.color = color;
  }

  public String getColor() {
    return color;
  }

  public void charge() {
    barCount = MAX_BARS;
  }

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

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

[MOD: edited code block - srh]

Steve Hunter
Steve Hunter
57,712 Points

Hi Muhammad,

Is this a question? What are you needing help with? Let me know and I'll try to assist.

Steve.

Muhammad Asif
PLUS
Muhammad Asif
Courses Plus Student 557 Points
Muhammad Asif
Muhammad Asif
Courses Plus Student 557 Points

hi steve i am stucked solving this code Protect the call to kart.drive by handling the IllegalArgumentException that is thrown when not enough battery remains. Print out the message from the exception to the screen as you catch the exception.

class Example {

  public static void main(String[] args) {
    GoKart kart = new GoKart("purple");
    if (kart.isBatteryEmpty()) {
      System.out.println("The battery is empty");
    }
   try {
      kart.drive(42); // existing line
    } catch(IllegalArgumentException e) {
      System.out.println(e);
    }    
  }
Steve Hunter
Steve Hunter
57,712 Points

Hi Muhammed,

Can you get me a link to the challenge - I want to test my answer as its likely to need tweaking.

I think your code looks OK but you might need to call getMessage() on e to make it printable?

So, System.out.println(e.getMessage());