Class Code 3/19/2018 - Linked Lists with Generics and Iterator

LinkedList.java

import java.util.Iterator;

public class LinkedList<T> implements Iterable<T> {

    private class Node<T> {
        T data;
        Node<T> next;

        public Node(T data){
            this.data = data;
        }

        public Node(T data, Node<T> next){
            this(data);
            this.next = next;
        }

        public String toString(){
            return "" + data;
        }
    }
    
    public class LLIterator<U> implements Iterator<U> {
        LinkedList<U> ll;
        LinkedList<U>.Node<U> curr;

        public LLIterator(LinkedList<U> ll){
            this.ll = ll;
            curr = null;
        }

        public boolean hasNext(){
            if (curr == ll.tail && ll.tail != null) return false;
            return true;
        }

        public U next(){
            if (curr == null)
                curr = ll.head;
            else curr = curr.next;
            return curr.data;
        }
    }

    private Node<T> head, tail;
    private int count;

    public LinkedList(){
        count = 0;
    }

    public void prepend (T i){
        if (count == 0){
            head = tail = new Node<T>(i);
        }
        else {
            head = new Node<T>(i, head);
        }
        count++;
    }

    public void append(T i){
        if (count == 0){
            head = tail = new Node<T>(i);
        }
        else {
            tail = tail.next = new Node<T>(i);
        }
        count++;
    }

    public int size(){
        return count;
    }

    public boolean isEmpty(){
        return head == null;
    }

    public String toString() {
        String retVal = "Linked list with " + count + " elements\nNodes:";
        //Node temp = head;
        //while(temp != null){
        //    retVal += temp + " ";
        //    temp = temp.next;
        //}

        for (Node<T> temp = head; temp != null; temp = temp.next)
            retVal += temp + " ";
        
        return retVal;
    }

    public Iterator<T> iterator(){
        return new LLIterator<T>(this);
    }
}

import java.util.Iterator;

public class LinkedList<T> implements Iterable<T> {

private class Node<T> {

T data;

Node<T> next;

public Node(T data){

this.data = data;

}

public Node(T data, Node<T> next){

this(data);

this.next = next;

}

public String toString(){

return "" + data;

}

public class LLIterator implements Iterator {

LinkedList ll;

LinkedList.Node curr;

public LLIterator(LinkedList ll){

this.ll = ll;

curr = null;

}

public boolean hasNext(){

if (curr == ll.tail && ll.tail != null) return false;

return true;

}

public U next(){

if (curr == null)

curr = ll.head;

else curr = curr.next;

return curr.data;

}

private Node<T> head, tail;

private int count;

public LinkedList(){

count = 0;

}

public void prepend (T i){

if (count == 0){

head = tail = new Node<T>(i);

}

else {

head = new Node<T>(i, head);

}

count++;

}

public void append(T i){

if (count == 0){

head = tail = new Node<T>(i);

}

else {

tail = tail.next = new Node<T>(i);

}

count++;

}

public int size(){

return count;

}

public boolean isEmpty(){

return head == null;

}

public String toString() {

String retVal = "Linked list with " + count + " elements\nNodes:";

//Node temp = head;

//while(temp != null){

// retVal += temp + " ";

// temp = temp.next;

//}

for (Node<T> temp = head; temp != null; temp = temp.next)

retVal += temp + " ";

return retVal;

}

public Iterator<T> iterator(){

return new LLIterator<T>(this);

}

IteratorEx.java

import java.util.ArrayList;
import java.util.Iterator;

public class IteratorEx {
    public static void main(String[] args){
        LinkedList<String> ships = new LinkedList<>();
        ships.append("Enterprise");
        ships.append("Voyager");
        ships.append("Defiant");
        
        Iterator<String> it = ships.iterator();

        String out = "";

        while(it.hasNext())
            out += it.next();

        System.out.println(out);

        out = "";
        for (String s : ships)
            out += s;

        System.out.println(out);
    }

    Node<String> n = new Node<>("hi");
}

import java.util.ArrayList;

import java.util.Iterator;

public class IteratorEx {

public static void main(String[] args){

LinkedList<String> ships = new LinkedList<>();

ships.append("Enterprise");

ships.append("Voyager");

ships.append("Defiant");

Iterator<String> it = ships.iterator();

String out = "";

while(it.hasNext())

out += it.next();

System.out.println(out);

out = "";

for (String s : ships)

out += s;

System.out.println(out);

}

Node<String> n = new Node<>("hi");

}

Hi There!

Class Code 3/19/2018 – Linked Lists with Generics and Iterator

LinkedList.java

IteratorEx.java