Question

void list::load()
{
    item *current;
    item *prev;
    ifstream fin;

    fin.open("List.txt");


    prev = NULL;
    while(!fin.eof())
    {
        current=new item;
        if (first == NULL) // we set first the first time
            first = current;
        fin>>current->name;
        current->previous=prev;
        current->next = NULL;
        if (prev != NULL)
            prev->next=current;
        prev = current; // we store the current as the prev for next iteration
    }

    fin.close();
}

Translate to Java

Answer 1

I have written entire java code to test the code, you can only use the load() function inside list class for your question

Output:

CODE(contians comments explaining the code):

import java.io.File;

import java.util.Scanner;

//item class (this is a blueprint of doubly linked list node)

class item

{

item next;

item previous;

String name;

}

//list driver class

public class list

{

//first is the refernce to head of the list, initialized to null

item first=null;

//answer for your question

public void load()

{

//refernces current and prev of type item(pointing to doubly linked list's node)

item current,prev=null;

//open the file

File f=new File("List.txt");

try

{

//this must be in try-catch block, reading from a file

Scanner sc=new Scanner(f);

//loop until the end of the file

while(sc.hasNext())

{

//create a new node

current=new item();

//if head is null, newly created node is the head

if(first==null)

{

first=current;

}

//set the name of the current node as the value read from the file

current.name=sc.next();

//current's prev points to previous node

current.previous=prev;

//current is the last node so far, so current->next is null

current.next=null;

//prev will be null when loop runs first time, and null.next will result in exception

//so this condtion

if(prev!=null)

{

//previous node's next is newly created current node

prev.next=current;

}

//newly created node becomes the previous node

prev=current;

}

}

catch (Exception e)

{

//TODO: handle exception

}

}

//to display the list

public void display()

{

//loop until the end of the list and print each node's item

item f=first;

while(f!=null)

{

System.out.print(f.name+" ");

f=f.next;

}

System.out.println(" ");

}

//main function to test the result

public static void main(String[] args)

{

//create a list

list l=new list();

//load nodes

l.load();

//display the list

l.display();

}

}

Screenshot of the answer