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LinkedList in Java

java-display

June 22, 2017
Published By : Pratik Kataria
Categorised in:

  • Header: java.util.LinkedList<E> (where E denotes the type of elements in the collection)
  • Some of the useful methods:
    • addFirst(E e)
    • addLast(E e)
    • clear()
    • clone() – returns a shallow copy of the Linked List
    • contains(Object o) – returns true if list contains the object
    • get(int position)
    • getFirst()
    • getLast()
    • indexOf(Object o)
    • remove() – retrieves and removes the head of the list
    • remove(Object o) – removes first occurrence of the object o.
    • removeFirst()
    • removeLast()
    • set(int position, E e)
    • size()
    • toArray()

EXAMPLE

import java.util.*;
import java.io.*;

class Book {
	int id;
	String name;

	public Book(int id, String name) {
		this.id = id;
		this.name = name;
	}

}

public class JavaLinkedList {

	public static void main( String []args) {
		//Creating list of type Book which is our custom data type now through class
		LinkedList<Book> list = new LinkedList<Book>();
		Book b1 = new Book(1, "To kill a mocking bird");
		Book b2 = new Book(2, "Java for Beginners");

		list.add(b1);

		list.add(1, b2);

		for(Book b: list)
			System.out.println(b.id + " " + b.name);

		/*

		Another way to print:

		Iterator<String> itr = list.iterator();

		while( itr.hasNext() )
			System.out......

		*/

	}

}

/*
OUTPUT:
1 To kill a mocking bird
2 Java for Beginners
*/

MORE FUNCTIONS

import java.util.*;
import java.io.*;

class Book {
	int id;
	String name;

	public Book(int id, String name) {
		this.id = id;
		this.name = name;
	}

}

public class LinkedListSnippets {

	public static void main( String []args) {
		LinkedList<Book> list = new LinkedList<Book>();
		Book b1 = new Book(1, "To kill a mocking bird");
		Book b2 = new Book(2, "Java for Beginners");

		list.add(b1);
		list.add(1, b2);
		list.addFirst(new Book(0, "addFirst"));
		list.addLast(new Book(list.size(), "addLast"));

		LinkedList<Book> cloneList = (LinkedList<Book>) list.clone();

		cloneList.remove();	//removing addFirst
		cloneList.remove(b2); //removing Java for Beginners
		cloneList.removeLast(); //removing addLast

		for(Book b: list)
			System.out.println(b.id + " " + b.name);

		System.out.println("---------------");
		System.out.println("CLONE");
		System.out.println("---------------");

		for(Book b: cloneList)
			System.out.println(b.id + " " + b.name);		

		System.out.println("---------------");

		Book arrOfBooks[] = new Book[list.size()];
		arrOfBooks = list.toArray(arrOfBooks);

		for(Book b: arrOfBooks)
			System.out.println(b.id + " " + b.name);


	}

}

/*
OUTPUT:
0 addFirst
1 To kill a mocking bird
2 Java for Beginners
3 addLast
---------------
CLONE
---------------
1 To kill a mocking bird
---------------
0 addFirst
1 To kill a mocking bird
2 Java for Beginners
3 addLast
*/