java.lang.NullPointerException When calling an int array

Question

I am very new to java and I have been stuck on this for a few hours now. Whevenever I try to call organizeBallots() I get the exception. From what I read, I have not initialized regionBallots correctly or that something is null. To me, it looks like I have initialized the array correctly and since its an int, it should be 0, not null. ...But I guess Im wrong, any help is greatly appreciated!

Edit: As I said I am new so Im not sure if it helps, but organizeBallots() is being called by another method in another class.

int[] regionBallots;        
regionBallots = new int[9];



public int[] organizeBallots( int incoming )
{

    if ( incoming >= 1 && incoming <= 10 )
        regionBallots[0]++;    // I get the exception here

    else if ( incoming >= 11 && incoming <= 20 )
        regionBallots[1]++;


    return regionBallots;

}

What exception you get? NullPointerException? Try to System.out.println(regionalBallots) to check if it is null. — Piotr Kochański
– Piotr Kochański, Commented Apr 13, 2012 at 20:18
the first line is a decleration at the beginning of the class while the second line is in the constructor of the same class. @PiotrKochanski yeah its a NullPointerException. — bzach
– bzach, Commented Apr 13, 2012 at 20:33

Petar Minchev · Accepted Answer · 2012-04-13 20:16:31Z

2

Make it like this: int[] regionBallots = new int[9];

You can't write code outside methods, except in initializers. To use an initializer write:

{
  //here the initializing code
}

To use a static initializer write:

static {
    //here the static initializing code
}

edited Apr 13, 2012 at 20:16

answered Apr 13, 2012 at 20:11

Petar Minchev

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9 Comments

Kirk Woll Over a year ago

Wouldn't that result in a compiler error, rather than an exception as the OP stated?

millimoose Over a year ago

-1: this is patently false. Java supports expressions in field initialisers.

Petar Minchev Over a year ago

@Inerdial - Yes, but he hasn't put the code in an initialiser.

millimoose Over a year ago

I do Set foo = new HashSet(); to declare fields all the time. That's not where the problem is.

Tom Crockett Over a year ago

Yes, the OP hasn't given enough info. My guess is he's initializing regionBallots in a constructor but calling organizeBallots before he manages to do that.

|

Piotr Kochański · Accepted Answer · 2012-04-13 20:50:07Z

1

This code worked for me without any issues:

public class T {

    int[] regionBallots;

    public T() {
        regionBallots = new int[9];
    }

    public int[] organizeBallots(int incoming) {

        if (incoming >= 1 && incoming <= 10)
            regionBallots[0]++; //

        else if (incoming >= 11 && incoming <= 20)
            regionBallots[1]++;

        return regionBallots;

    }

    public static void main(String[] args) {
        T t = new T();
        for (int i = 0; i < 100; i++) {         
              System.out.println(t.organizeBallots(i));
              System.out.println(t.organizeBallots(i)[0]);
              System.out.println(t.organizeBallots(i)[1]); 
        }
    }

}

answered Apr 13, 2012 at 20:50

Piotr Kochański

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2 Comments

bzach Over a year ago

Just out of curiousity, what did you do differently? This looks like exactly what I did haha

Piotr Kochański Over a year ago

Hard to say. I did not see any problem with your code. Try to debug your code to see if regionBallots is not null in organizeBallots method.

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