NullPointer Exception erro

Question

Essentially, this code should take input from user for:trip description, miles of trip, and gallons of gas used. That info should be placed into an array for each, then have the MPG for each trip calculated. In the end I want it to display a listing that includes: name, miles traveled and the MPG for each trip.

The problem I am having is that the code compiles, but when executed I receive:

Exception in thread "main" java.lang.NullPointerException at week6challenge.Week6Challenge.main(Week6Challenge.java:25) Java Result: 1"

I am still VERY new to programming and I have searched for solutions all over, but I cannot find how to fix it. I learned what the problem is, but an clueless as to how to fix it. Any help would be GREATLY appreciated. Thanks!

Code:

import java.util.Scanner;
public class Week6Challenge {

    public static void main(String[] args) {
        Scanner scan = new Scanner (System.in);
        int count = 0;
        String[] tripName = null;
        double[] tripMiles = null;
        double[] tripMPG = null;
        double miles = 0, gallons = 0;

        while (count <= 10){
            System.out.println("Enter a description of this trip");
            tripName[count] = scan.next();
            count++;

            System.out.println("How many miles did you drive?");
            tripMiles[count] = scan.nextDouble();

            System.out.println("How many gallons of gas did you use on this trip");
            tripMPG[count] = answer(miles, gallons);
        }
        int k = 0;
        System.out.println("Trip Name \t Miles Traveled \t MPG");

        while(k < 10){
            System.out.println(tripName[k]+ "\t" + tripMiles[k] + "\t" + tripMPG[k]);
            k = k++;
        }
    }

    public static double answer(double num1, double num2){
        return (num1 / num2);
    }    
}

NullPointerException errors are always solved the same way: find out which object is null. — Robert Harvey, Apr 25 '15 at 14:28
This may give you a hint. http://stackoverflow.com/questions/1200621/declare-array-in-java — Michael Petch, Apr 25 '15 at 14:30
`while (k < 10)` should probably be a `for` loop. Notice that you said `while (count <= 10)` above that. Notice the difference? Dont say `k=k++;` just say `k++`. — Robert Harvey, Apr 25 '15 at 14:33
You didn't assign an actual array object to `tripName`. Notice it says `String[] tripName = null;`? Which is exactly what the error message is telling you. — Robert Harvey, Apr 25 '15 at 14:35
I think I know which object is null, but I don't know how to fix it. Sorry guys, I am trying. I'm just super new. — Jon Cagle, Apr 25 '15 at 14:36
@RobertHarvey, how can I assign an array object like you mentioned? — Jon Cagle, Apr 25 '15 at 14:38
http://stackoverflow.com/questions/1200621/declare-array-in-java — Robert Harvey, Apr 25 '15 at 14:41
@JonCagle Please see Robers link to know how to declare an array in Java, but you should know, that the array size should at least be **11**. If you use a lower value, then you'll get an `ArrayIndexOutOfBoundsException`. — Tom, Apr 25 '15 at 14:49

NullPointer Exception erro

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