Question

you will write two versions of a function that calculates the sum of all the numbers in a LinkedList. In the first version, you should use an iterator and either a while loop or a traditional for loop to compute the sum . In the second version, you should use the range - based for loop. Write one or more tests in a main() function that demonstrate that either version of your function works as intended.

I would personally like to just know how the functions should be written so I can finish this problem without any trouble. I mainly want to know how to write the iterator with the loops, the range-based loop on how that can be done, and finally, how to write the tests to make it work.

Answer 1

Hi, I have taken two versions of a function but taking two functions to explain 2 versions.

1) sumVersion1() - calculates the sum of all the numbers in a LinkedList using an Iterator

2) sumVersion2() - calculates the sum of all the numbers in a LinkedList using the range-based for loop

Program

import java.util.*;

class LinkedListSumDemo
{
public static int sumVersion1(LinkedList<Integer> l1)
{
Iterator<Integer> i1=l1.iterator();
int sum=0;
while(i1.hasNext())
{
sum=sum+i1.next();
}
return sum;
}

public static int sumVersion2(LinkedList<Integer> l1)
{
int lowLimit,uppLimit;
Scanner sc=new Scanner(System.in);
System.out.print("\n\nEnter a lowerLimit(must be greater than or equal to 0) index : ");
lowLimit=sc.nextInt();
System.out.print("Enter a upper Limit(must be less than the size of LinkedList) index: ");
uppLimit=sc.nextInt();
int sum=0;
for(int i=lowLimit;i<=uppLimit;i++)
{
sum=sum+l1.get(i);
}
return sum;
}

public static void main(String args[])
{
LinkedList<Integer> l1=new LinkedList<Integer>();
Scanner sc=new Scanner(System.in);
System.out.print("\nHow many numbers do you want in your list: ");
int nums=sc.nextInt();
int num;
for(int i=0;i<nums;i++)
{
System.out.print("Enter number "+(i+1)+": ");
num=sc.nextInt();
l1.add(num);
}

System.out.println("\nElements of a LinkedList: "+l1);

System.out.println("\n\nVersion1: ");
System.out.println("------------------------------------------------------");
System.out.println("\nThe sum of all the numbers using an Iterator: "+sumVersion1(l1));
System.out.println("\n\nVersion2: ");
System.out.println("------------------------------------------------------");
System.out.println("\nThe sum of all the numbers within a range: "+sumVersion2(l1));
System.out.println("\n");
}
}

Output: