Why wont the system print out my average?

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Java

In my coding class we learning to print out the average of a set of numbers from an array list. I know how to print the average of a single array but I am having trouble with printing out the average of a double array. The context of my problem is to ask the user for height and width of the array, then ask for a minimum and maximum number. Where it will randomly find numbers and print them out however many times the height and width was given. Now I have to calculate and display the rainfall for the entire array. The whole code works except when I try to do this. Can anyone help me. I have a problem showing I know how to print out the average of a specific set of numbers, but I can't seem to figure out how to do it in my homework. Should I be using the .size() method in my for loops to figure out the average? Thanks

What I have tried:

From the problem that works:

import java.util.ArrayList;
import java.util.Scanner;

public class ArrayListAverage {
   public static void main (String [] args) {
      final int NUM_ELEMENTS = 8;
      Scanner scnr = new Scanner(System.in);
      ArrayList<Double> userNums = new ArrayList<Double>(); // User numbers
      Double sumVal = 0.0;
      Double averageVal = 0.0; // Computed average
      int i = 0; // Loop index

      System.out.println("Enter " + NUM_ELEMENTS + " numbers...");
      for (i = 0; i < NUM_ELEMENTS; ++i) {
         System.out.print("Number " + (i + 1) + ": ");
         userNums.add(new Double(scnr.nextDouble()));
      }

      // Determine average value
      sumVal = 0.0;
      for (i = 0; i < NUM_ELEMENTS; ++i) {
         sumVal = sumVal + userNums.get(i); // Calculate sum of all numbers
      }

      averageVal = sumVal / NUM_ELEMENTS; // Calculate average 
      
      System.out.println("Average: " + averageVal);

      return;
   }
}

The code that doesn't work:

import java.util.Scanner;
import java.util.Random;
public class App {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        
        int userHeight;
        int userWidth;
        int userMin;
        int userMax;
        
        
        System.out.println("Please enter in a height and width of array.");
        System.out.print("Height: ");
        userHeight = scan.nextInt();
        System.out.print("Width: ");
        userWidth = scan.nextInt();
        
        System.out.println("Please enter in the minimum and maximum rainfall value.");
        System.out.print("Minimum rainfall: ");
        userMin = scan.nextInt();
        System.out.print("Maximum rainfall: ");
        userMax = scan.nextInt();
        
        int [][] rainMap = new int [userHeight][userWidth];
        
        for (int i = 0; i < userHeight; i++)
        {
            for (int j = 0; j < userWidth; j++)
            {
                Random rand = new Random();
                int randomNum = rand.nextInt((userMax - userMin) + 1) + userMin;
                rainMap[i][j] = randomNum;
            }
        }
        
        for (int i = 0; i < userHeight; i++)
        {
            for (int j = 0; j < userWidth; j++)
            {
                System.out.print(rainMap[i][j]);
            }
            System.out.println("");
        }
       
        //finding average
        double total = 0;
        double sumValI = 0;
        //double sumValJ = 0;
        double average = 0.0;
       for (int i = 0; i < userHeight; i++)
       {
           for (int j = 0; j < userWidth; j++)
           {
               sumValI = sumValI + rainMap.get((i)(j));
           }
       }
       total = userHeight * userWidth; 
        average = sumValI / total;
        System.out.println("Average rainfall: " + average);
    }
    
}