LinkedList Methods

Question 1

Declaring a LinkedList

Answer 1

LinkedList linkedlist = new LinkedList();

Question 2

Adding an Item at first of the LinkedList

Answer 2

Method 1 linkedlist.addfirst(“First-Element”);

Method 2 linkedlist.push(“New-Element”);

Question 3

Adding an Item at Last of the LinkedList

Answer 3

Method 1 linkedlist.addlast(“Last-Element”);

Method 2 linkedlist.add(“Last-Element”);

Question 4

Adding an element at a particular position of LinkedList

Answer 4

linkedlist.add(3,Element);

Question 5

Removing the first Item from the LinkedList

Answer 5

Method 1 linkedlist.removefirst();
Method 2 linkedlist.pop();
Method 3 linkedlist.poll();
Method 4 linkedlist.pollfirst();

Question 6

Removing the last Item from the LinkedList

Answer 6

Method 1 linkedlist.removelast();

Method 2 linkedlist.polllast();

Question 7

Removing an Item from the LinkedList (Any Element)

Answer 7

linkedlist.remove(“Element”);

Question 8

Removing an Item from a particular position of an LinkedList

Answer 8

linkedlist.remove(2);

Question 9

Retrieving an Item from an LinkedList based on the Index

Answer 9

Object X = linkedlist.get(5);

Question 10

Retrieving first Item from an LinkedList

Answer 10

Method 1 Object FirstElement = linkedlist.getfirst();
Method 2 Object FirstElement = linkedlist.peek();
Method 3 Object FirstElement = linkedlist.peekfirst();

Question 11

Retrieving last Item from an LinkedList

Answer 11

Method 1 Object LastElement = linkedlist.getlast();

Method 2 Object LastElement = linkedlist.peeklast();

Question 12

Retrieving first occurrence of Item from an LinkedList - Returns Index

Answer 12

linkedlist.indexof(“Element”);

Question 13

Retrieving last occurrence of Item from an LinkedList - Returns Index

Answer 13

linkedlist.lastindexof(“Element”);

Question 14

Updating the value of the element at a particular index in an LinkedList

Answer 14

linkedlist.set(2,”New-Value-Of-The-Element”)

Question 15

Size of an LinkedList

Answer 15

linkedlist.size();

Question 16

Duplicate a linkedlist to another linkedlist

Answer 16

DuplicateLinkedlist = linkedlist.clone();

Question 17

Iterating over an LinkedList (Forward) (Method 1: For Loop)

Answer 17

Method 1 - FOR LOOP
for (int counter = 0; counter < linkedlist.size(); counter++) {
System.out.println(arraylist.get(counter));

Question 18

Iterating over an LinkedList (Forward) (Method 2: While Loop)

Answer 18

Method 2 - WHILE LOOP 
int count = 0; 		
while (linkedlist.size() > count) {
    System.out.println(arraylist.get(count));
    count++;
     }

Question 19

Iterating over an LinkedList (Forward) (Method 3: ITERATOR )

Answer 19

Method 3 - ITERATOR
Iterator iterator = linkedlist.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}

Question 20

Iterating over an LinkedList (Backward)

Answer 20

BACKWARD ITERATING
ListIterator iterator = linkedlist.iterator();
while (iterator.hasPrevious()) {
System.out.println(iterator.previous());

Question 21

Is this Item there in the LinkedList

Answer 21

linkedlist.contains(“Element”);

Question 22

Difference Between ArrayList And LinkedList

Answer 22

ArrayList and LinkedList both implements List interface and their methods and results are almost identical. However there are few differences between them which make one better over another depending on the requirement. ArrayList Vs LinkedList

Search: ArrayList search operation is pretty fast compared to the LinkedList search operation. get(int index) in ArrayList gives the performance of O(1) while LinkedList performance is O(n).Reason: ArrayList maintains index based system for its elements as it uses array data structure implicitly which makes it faster for searching an element in the list. On the other side LinkedList implements doubly linked list which requires the traversal through all the elements for searching an element.
Deletion: LinkedList remove operation gives O(1) performance while ArrayList gives variable performance: O(n) in worst case (while removing first element) and O(1) in best case (While removing last element).Conclusion: LinkedList element deletion is faster compared to ArrayList.Reason: LinkedList’s each element maintains two pointers (addresses) which points to the both neighbor elements in the list. Hence removal only requires change in the pointer location in the two neighbor nodes (elements) of the node which is going to be removed. While In ArrayList all the elements need to be shifted to fill out the space created by removed element.
Inserts Performance: LinkedList add method gives O(1) performance while ArrayList gives O(n) in worst case. Reason is same as explained for remove.
Memory Overhead: ArrayList maintains indexes and element data while LinkedList maintains element data and two pointers for neighbor nodes hence the memory consumption is high in LinkedList comparatively.

Question 23

Similarities between ArrayList and LinkedList

Answer 23

Both ArrayList and LinkedList are implementation of List interface.
They both maintain the elements insertion order which means while displaying ArrayList and LinkedList elements the result set would be having the same order in which the elements got inserted into the List.
Both these classes are non-synchronized and can be made synchronized explicitly by using Collections.synchronizedList method.
The iterator and listIterator returned by these classes are fail-fast (if list is structurally modified at any time after the iterator is created, in any way except through the iterator’s own remove or add methods, the iterator will throw a ConcurrentModificationException).