Applications

LL

package com.gs.corejava.datastructures;

public class MySinglyLinkedList<T> {

	private class MyNode<E extends Object> {
		E data;
		MyNode<E> next = null;

		public MyNode() {
		}

		public MyNode(E data) {
			this.data = data;
		}
	}

	private MyNode<T> start;
	private int size = 0;
	private MyNode<T> currentNode;

	public MySinglyLinkedList() {
		start = new MyNode<T>();
		start.next = null;
	}

	public void add(T data) {
		MyNode<T> myNode = new MyNode<T>(data);
		MyNode<T> head = start;
		MyNode<T> prev = start;
		if (null == currentNode) {
			while (null != head) {
				prev = head;
				head = head.next;
			}
			currentNode = myNode;
			prev.next = currentNode;
		} else {
			currentNode.next = myNode;
			currentNode = myNode;
		}
		size++;
	}

	public void addFirst(T data) {
		MyNode<T> myNode = new MyNode<T>(data);
		MyNode<T> head = start;
		myNode.next = head.next;
		head.next = myNode;
		size++;
	}

	public void addLast(T data) {
		add(data);
	}

	public void add(T data, int index) {
		MyNode<T> myNode = new MyNode<T>(data);
		MyNode<T> head = start;
		MyNode<T> prev = start;
		int currentIndex = 0;
		while (null != head && currentIndex <= index) {
			prev = head;
			head = head.next;
			currentIndex++;
		}
		myNode.next = prev.next;
		prev.next = myNode;
		size++;
	}

	public MyNode<T> remove(T data) {
		MyNode<T> node = new MyNode<T>(data);
		MyNode<T> head = start;
		MyNode<T> prev = start;
		while (null != head) {
			if (null != node.data && node.data.equals(head.data)) {
				break;
			}
			prev = head;
			head = head.next;
		}
		prev.next = head.next;
		head = null;
		size--;
		return node;

	}

	public MyNode<T> remove(int index) {
		MyNode<T> head = start;
		MyNode<T> prev = start;
		int currentIndex = 0;
		while (null != head && currentIndex <= index) {
			prev = head;
			head = head.next;
			currentIndex++;
		}
		MyNode<T> myNodeToReturn = head;
		prev.next = head.next;
		head = null;
		size--;

		return myNodeToReturn;

	}

	public Object[] toArray() {
		Object[] array = new Object[size];
		int k = 0;
		MyNode<T> head = start.next;
		while (null != head) {
			array[k] = head.data;
			k++;
			head = head.next;
		}
		return array;

	}

}

package com.gs.corejava.datastructures;

public class TestLinkedList {

	public static void main(String[] args) {

		testIntegerLinkedListAdd();

		System.out.println("---for String objects---");

		testStringLinkedListAddMethod();

		System.out.println("---for Custom objects like Teacher----");

		testCustomObjLinkedListAdd();
	}

	/**
	 * 
	 */
	private static void testIntegerLinkedListAdd() {
		MySinglyLinkedList<Integer> linkedList = new MySinglyLinkedList<Integer>();

		linkedList.add(123);
		linkedList.add(456);
		linkedList.add(454);
		linkedList.add(224);

		linkedList.add(-80, 2);

		linkedList.addFirst(12);

		linkedList.remove(new Integer(454));
		linkedList.remove(2);

		Object[] arr = linkedList.toArray();
		for (int i = 0; i < arr.length; i++) {
			System.out.println(arr[i]);
		}
	}

	/**
	 * 
	 */
	private static void testCustomObjLinkedListAdd() {
		// ---------for Custom objects like Teacher-----------
		MySinglyLinkedList<Teacher> listOfTeacher = new MySinglyLinkedList<Teacher>();
		Teacher teacher1 = new Teacher(1, "Mohit");
		Teacher teacher2 = new Teacher(2, "Sumit");
		Teacher teacher3 = new Teacher(3, "Sahil");
		Teacher teacher4 = new Teacher(4, "Naveen");
		listOfTeacher.add(teacher1);
		listOfTeacher.add(teacher2);
		listOfTeacher.add(teacher3);
		listOfTeacher.add(teacher4);
		Object[] arrayOfTeacher = listOfTeacher.toArray();
		Teacher teacherObj;
		for (int i = 0; i < arrayOfTeacher.length; i++) {
			if (arrayOfTeacher[i] instanceof Teacher) {
				teacherObj = (Teacher) arrayOfTeacher[i];
				System.out.println(teacherObj);
			}
		}
	}

	/**
	 * 
	 */
	private static void testStringLinkedListAddMethod() {
		// -------for String objects-------
		MySinglyLinkedList<String> listOfNames = new MySinglyLinkedList<String>();
		listOfNames.add("Mohit");
		listOfNames.add("Rohit");
		listOfNames.add("Sumit");
		listOfNames.add("Amit");
		Object[] arrayOfNames = listOfNames.toArray();
		for (int i = 0; i < arrayOfNames.length; i++) {
			System.out.println(arrayOfNames[i]);
		}
	}

}

class Teacher {
	private int id;
	private String name;

	/**
	 * @param id
	 * @param name
	 */
	public Teacher(int id, String name) {
		super();
		this.id = id;
		this.name = name;
	}

	@Override
	public String toString() {
		return "Teacher [id=" + id + ", name=" + name + "]";
	}

}