Question

5. (40 Points) Write a complete Java class named ArrayMethods that implements the methods listed below. All the methods accept the following parameters: Parameters: intar An array of int values. int firstIndex The index of the first element to include in the sum. int lastIndex The index of the last element to include in the sum. Please note that all methods must verify the validity of first Index and lastIndex. public static int sum(int[] arr, int first Index, int lastIndex) This method will compute the sum of the elements in the parameter array arr starting at index firstIndex and ending at index lastIndex. Return Value: This method returns an int representing the computed sum of the elements in arr starting at first Index and ending at lastIndex. If either index is invalid, the method should return the value -666. public static double average(int[arr, int first Index, int lastIndex) This method will compute the average of the elements in the parameter array arr starting at index firstIndex and ending at index lastIndex. You should make use of the sum(int[] arr, int first Index, int lastIndex) method in your computation. Return Value: This method returns a double value representing the computed average of the elements in arr starting at index firstIndex and ending at index last Index. If either index is invalid, the method should return the value-666.0. public static int belowAverage(int[] arr, int first Index, int lastIndex) This method will search the elements in the parameter array arr, starting at index firstIndex and ending at index lastIndex, and count the number of elements that are below average. You should make use of the average(int[] arr, int firstIndex, int lastIndex) method in your computation. Return Value: This method returns the number of elements in the array arr, starting at index firstIndex and ending at index lastIndex, that are below average. If either index is invalid, the method should return the value -666. public static int aboveAverage(int[] arr, int first Index, int last Index) This method will search the elements in the parameter array art, starting at index firstIndex and ending at index lastIndex, and count the number of elements that are above average. You should make use of the average(int[] arr, int firstIndex, int lastIndex) method in your computation. Return Value: This method returns the number of elements in the array arr, starting at index firstIndex and ending at index lastIndex, that are above average. If either index is invalid, the method should return the value -666.

Answer 1

We will just iterate through the array and find the sum of the elements in the first method.

Then we will use the sum() method to implement the avergae() method.

And then, we will use the average() method to implement the aboveAverage() and belowAverage() methods.

I have also tested the methods on a sample array.

Here's the code.

import java.util.*;
import java.lang.*;
import java.io.*;

class ArrayMethods
{
public static int sum(int[] arr, int firstIndex, int lastIndex){
if(firstIndex < 0 || lastIndex >= arr.length || firstIndex > lastIndex){
return -666;
}
  
int sum = 0;
for(int i = firstIndex; i <= lastIndex; i++){
sum += arr[i];
}
  
return sum;
}
  
public static double average(int[] arr, int firstIndex, int lastIndex){
double avg = 0;
  
double sum = sum(arr, firstIndex, lastIndex);
avg = sum / (lastIndex - firstIndex);
  
return avg;
}
  
public static int belowAverage(int[] arr, int firstIndex, int lastIndex){
double avg = average(arr, firstIndex, lastIndex);
int count = 0;
  
for(int i = firstIndex; i <= lastIndex; i++){
if(arr[i] < avg){
count++;
}
}
  
return count;
}
public static int aboveAverage(int[] arr, int firstIndex, int lastIndex){
double avg = average(arr, firstIndex, lastIndex);
int count = 0;
  
for(int i = firstIndex; i <= lastIndex; i++){
if(arr[i] > avg){
count++;
}
}
  
return count;
}
  
   public static void main (String[] args){
   int[] arr = {23, 367, 36, 26, 82, 7, 38, 18, 75};
  
   System.out.println(sum(arr, 1, 6));
   System.out.println(average(arr, 1, 6));
   System.out.println(aboveAverage(arr, 1, 6));
   System.out.println(belowAverage(arr, 1, 6));
   }
}

Here are the screenshots of the code and the output.

import java.util.*; import java.lang.*; import java.io.*; class ArrayMethods public static int sum(int[] arr, int first Index, int lastIndex) { if(firstIndex < 0 || lastIndex >= arr. length || firstIndex > lastIndex) { return -666; int sum = 0; for(int i = firstIndex; i <= lastIndex; i++){ sum += arr[i]; return sum; public static double average (int[] arr, int first Index, int lastIndex) { double avg = 0; double sum = sum(arr, firstIndex, lastIndex); avg = sum / (lastIndex - firstIndex); return avg; public static int belowAverage (int[] arr, int first Index, int lastIndex) { double avg = average (arr, firstIndex, lastIndex); int count = 0; for(int i = firstIndex; i <= lastIndex; i++){ if(arr[i] < avg) { count++; return count; public static int aboveAverage (int[] arr, int first Index, int lastIndex) { double avg = average (arr, firstIndex, lastIndex); int count = 0; for(int i = firstIndex; i <= lastIndex; i++){ if(arr[i] > avg) { count++; co return count; public static void main (String[] args) { int[] arr = {23, 367, 36, 26, 82, 7, 38, 18, 75}; System.out.println(sum(arr, 1, 6)); System.out.println(average (arr, 1, 6)); System.out.println(aboveAverage (arr, 1, 6)); System.out.println(belowAverage (arr, 1, 6));

Let me know if you have any doubts in the comments. Please upvote if the answer helped you.

Output 556 111.2