class Node{
    int num;
    Node next;
}

Write an algorithm or a method to find and display the sum of even integers from an existing linked list.
The method declaration is as follows:
void sumEvenNode(Node str)

void sumEvenNode(Node str){
    int sum = 0;
    if(str == null)
        System.out.println("Sum = 0");
    else{
        while(str != null){
            if(str.num % 2 == 0)
                sum += str.num;
            str = str.next;
    }
    System.out.println("Sum = " + sum);
}