Question

// Java Queue LinkedList Assignment

// A queue is implemented using a singly linked list.
// the variable: back "points" at the first node in the linked list
// new elements ( enqueued) are added at the back
// the variable: front "points" at the last node in the linked list.
// elements are removed (dequeued) from the front
//
// Several queue instance methods are provided for you; do not change these
// Other instance methods are left for you as "ToDo" tasks
//
// You may not use any other Java classes or algorithms in completing the ToDo items
// You may not add any instance variables to the class
// You may add your own private instance methods for modularity sake
//
public class Practice {

   private Node front, back;

   static class Node {
       public Node (char item, Node next) { this.item = item; this.next = next; }
       public char item;
       public Node next;
   }

//This is the problem to solve.

   // toString
   // the function toString returns a single String consisting of all the characters in the queue.
   // the leftmost character in the returned string should be the character at the FRONT of the queue
   // Example; if the linked list representation is: back--> 'a' 'b' 'c' 'd' <-- front
   // the returned string would be "dcba"
   // a normal traversal of the linked structure from back to front would give us the string we want REVERSED
   //
   // You may not use any other Java classes ( e.g. ArrayList, ) to solve this.
   // You may use basic java arrays and methods of the String class
   //
   // Hint1: you can build a String by starting with the empty string and the concatenating characters as shown below
   // String x ="";
   // x = x + 'q'; // adds 'q' onto the right end of String x
   // Hint2: recursion is one way to handle the reversal issue

   public String toString() {
       return ""; // TODO 1 fix this

   }

Answer 1

code:

public String toString() {
// set str to "" we will add other values later
String str = "";
// create a temp node
Node temp = front;
// traverse till temp becomes null
while (temp != null) {
// add item to str
str = temp.item + str;
// move temp forward
temp = temp.next;
}
  
// retuirn str
return str;
}

screenshot:

public String toString({ // set str to "" we will add other values Later String str = ""; // create a temp node Node temp = front; // traverse till temp becomes null while (temp != null) { // add item to str str = temp.item + str; // move temp forward temp = temp.next; // retuirn str return str;