Question

JAVA- Complete the code by following guidelines in comments.

class CircularList

{

private Link current;

private Link prev;

public CircularList() {

// implement: set both current and prev to null

}

public boolean isEmpty() {

// implement

return true;

}

public void insert(int id) {

// implement: insert the new node behind the current node

}

public Link delete() {

// implement: delete the node referred by current

return null;

}

public Link delete(int id) {

// implement: delete the node with value id

// if no node with the id exists, return null

return null;

}

public void displayList() {

// implement: print all the list element values once, each value

seperated by comma

}

}

class Link

{

private int id;

private Link next;

public Link(int id) {

// implement

}

public String toString() {

return String.valueOf(id);

}

}

public class Lab5

{

public static void main(String[] args) {

CircularList theList = new CircularList();

theList.insert(10);

theList.insert(20);

theList.insert(15);

theList.insert(5);

theList.insert(30);

theList.displayList();

System.out.println(theList.delete());

theList.delete(15);

theList.displayList();

while (!theList.isEmpty()) {

Link aLink = theList.delete();

System.out.println("Deleted: " + aLink);

}

if (!theList.isEmpty())

System.out.println("Program error");

else

System.out.println("Program success");

}

}

Answer 1

Below I have copied your code and completed it as per the guidelines-

class CircularList

{

private Link current;

private Link prev;

public CircularList() {

current=null;

prev=null;

// implement: set both current and prev to null

}

public boolean isEmpty() {

return(current==null);

// implement

}

public void insert(int id)

{

Link newlink = newlink(id);

if(current == null)

{

current = prev = newLink;

}

else

{

  current.previous = newlink;
}
prev = newLink;
newLink.next = current

// implement: insert the new node behind the current node

}

public Link delete()

{

Link temp = current;

if(current.next == null)

{

current = null;

return;

}

else

{

current.id = current.next.id;

temp = current.next;

temp = null;

current.next = current.next.next;

// implement: delete the node referred by current

}

public Link delete(int id)

{

if( current.id == id)

{

current.previous = current;

current.previous.previous = prev;

}

else

{

while(current.id != id)

{

current = current.previous;

if( current == null)

return null; // not found

}

if ( current == prev )

{

current=prev.next;

prev = prev.previous;

}

// implement: delete the node with value id

// if no node with the id exists, return null

return null;

}

public void displayList()

{

System.out.println("Values in the list are")'

while(prev != null)

{

System.out.println(current.id +" , ");

current=current.previous;

prev=prev.previous;

}

// implement: print all the list element values once, each value

seperated by comma

}

class Link

{

private int id;

private Link next;

public Link(int id1)

{

id1=id

}

// implement

}

public String toString() {

return String.valueOf(id);

}

}

public class Lab5

{

public static void main(String[] args) {

CircularList theList = new CircularList();

theList.insert(10);

theList.insert(20);

theList.insert(15);

theList.insert(5);

theList.insert(30);

theList.displayList();

System.out.println(theList.delete());

theList.delete(15);

theList.displayList();

while (!theList.isEmpty()) {

Link aLink = theList.delete();

System.out.println("Deleted: " + aLink);

}

if (!theList.isEmpty())

System.out.println("Program error");

else

System.out.println("Program success");

}

}