Wednesday, April 28, 2010

Linked List using java

Linked list  is implementation of the List interface. LinkedList class provides uniformly named methods to get, remove and insert an element at the beginning and end of the list

Hierarchies of LinkedList follows as :

java.lang.Object
  extended by java.util.AbstractCollection
      extended by java.util.AbstractList
          extended by java.util.AbstractSequentialList
              extended by java.util.LinkedList
I have list down Linked list methods which are provided as LinkList J2SE6 API documentation
so one can get basic idea what are the methods available and there is simple java program provided
at bottom of current  linkedlist post so you can  play with other methods.


  
boolean add(E e)
          Appends the specified element to the end of this list.
 void add(int index, E element)
          Inserts the specified element at the specified position in this list.
 boolean addAll(Collection< extends E> c)
          Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator.
 boolean addAll(int index, Collection<? extends E> c)
          Inserts all of the elements in the specified collection into this list, starting at the specified position.
 void addFirst(E e)
          Inserts the specified element at the beginning of this list.
 void addLast(E e)
          Appends the specified element to the end of this list.
 void clear()
          Removes all of the elements from this list.
 Object clone()
          Returns a shallow copy of this LinkedList.
 boolean contains(Object o)
          Returns true if this list contains the specified element.
 Iterator<E> descendingIterator()
          Returns an iterator over the elements in this deque in reverse sequential order.
 E element()
          Retrieves, but does not remove, the head (first element) of this list.
 E get(int index)
          Returns the element at the specified position in this list.
 E getFirst()
          Returns the first element in this list.
 E getLast()
          Returns the last element in this list.
 int indexOf(Object o)
          Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
 int lastIndexOf(Object o)
          Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
 ListIterator<E> listIterator(int index)
          Returns a list-iterator of the elements in this list (in proper sequence), starting at the specified position in the list.
 boolean offer(E e)
          Adds the specified element as the tail (last element) of this list.
 boolean offerFirst(E e)
          Inserts the specified element at the front of this list.
 boolean offerLast(E e)
          Inserts the specified element at the end of this list.
 E peek()
          Retrieves, but does not remove, the head (first element) of this list.
 E peekFirst()
          Retrieves, but does not remove, the first element of this list, or returns null if this list is empty.
 E peekLast()
          Retrieves, but does not remove, the last element of this list, or returns null if this list is empty.
 E poll()
          Retrieves and removes the head (first element) of this list
 E pollFirst()
          Retrieves and removes the first element of this list, or returns null if this list is empty.
 E pollLast()
          Retrieves and removes the last element of this list, or returns null if this list is empty.
 E pop()
          Pops an element from the stack represented by this list.
 void push(E e)
          Pushes an element onto the stack represented by this list.
 E remove()
          Retrieves and removes the head (first element) of this list.
 E remove(int index)
          Removes the element at the specified position in this list.
 boolean remove(Object o)
          Removes the first occurrence of the specified element from this list, if it is present.
 E removeFirst()
          Removes and returns the first element from this list.
 boolean removeFirstOccurrence(Object o)
          Removes the first occurrence of the specified element in this list (when traversing the list from head to tail).
 E removeLast()
          Removes and returns the last element from this list.
 boolean removeLastOccurrence(Object o)
          Removes the last occurrence of the specified element in this list (when traversing the list from head to tail).
 E set(int index, E element)
          Replaces the element at the specified position in this list with the specified element.
 int size()
          Returns the number of elements in this list.
 Object[] toArray()
          Returns an array containing all of the elements in this list in proper sequence (from first to last element).
<T> T[]
toArray(T[] a)
          Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.
 
LinkedList Java Program :
 
package com.anuj.basic;

import java.util.Iterator;
import java.util.LinkedList;

/**
 *
 * @author Anuj Patel
 */
public class LinkedListOperation {

    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.add(5);
        list.add(1);
        list.add(2);
        list.add(10);
        list.add(6);
        
        //iterate over list
        Iterator iterator = list.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

        System.out.println("First Element in LinkedList - " + list.getFirst());
        System.out.println("Last Element in LinkedList - " + list.getLast());
        
        //remove first element from list
        list.removeFirst();
        
        //remove last element from list
        list.removeLast();
        
        System.out.println("LinkedList after removing elements : ");
        iterator = list.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

    }
}

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