ArrayList Exceptions

[Gus Smith]

Hey guys, playing around with ArrayLists and trying to calculate various things with Rainfall using one. However, it keeps throwing exceptions whenever I try to interact with the ArrayList itself and I can't figure out why. Any hints or tips in the right direction would be appreciated, thanks.

public class Rainfall
{
    // instance variables - replace the example below with your own
    private ArrayList<Integer> rainfall;
    
    public Rainfall()
    {
        ArrayList rainfall = new ArrayList<Integer>();
    }
    
    /**
     * Adds rainfall data to the arraylist. Doesn't accept 0 or over 99999. 
     */
    public void addRainyDay(int data)
    {
        if(data >= 1 || data <= 99999)
        {
            rainfall.add(data);
        }
        else
        {
            System.out.println("Non-valid input.");
        }
    }
    
    /**
     * Calculates the number of rainy days, average amount of rainfall and the day it rained most.
     */
    public void getStatistics()
    {
        int average = 0;
        int rainyDays = rainfall.size();
        int maxRain = 0;
        for(int i = 0; i < rainfall.size(); i++)
        {
            average = ((average + rainfall.get(i)) / rainfall.size());
        }
        for(int i = 0; i < rainfall.size(); i++)
        {
            if(maxRain < rainfall.get(i))
            {
                maxRain = rainfall.get(i);
            }
        }
        System.out.println("No. of rainy days: " + rainyDays + "cm. Average rainfall: " + average + "cm. Maximum rain was on day: " + maxRain + ".");
    }
}

[Mori Gad]

// instance variables - replace the example below with your own   
    private ArrayList<Integer> rainfall;   
       
    public Rainfall()   
    {   
        ArrayList rainfall = new ArrayList<Integer>();   
    }

Your constructor is wrong, if you intend to use rainfall outside of it.

It should be

rainfall = new ArrayList<Integer>();   

The way you currently have it is creating a local scope variable rainfall.

[Gus Smith]

Thank you, should've seen that :p.