java - iterating a linked list

Question

if I use a for-each loop on a linked list in java, is it guaranteed that I will iterate on the elements in the order in which they appear in the list?

Answer 1

I found 5 main ways to iterate over a Linked List in Java (including the Java 8 way):

1. For Loop
2. Enhanced For Loop
3. While Loop
4. Iterator
5. Collections’s stream() util (Java8)

For loop

LinkedList<String> linkedList = new LinkedList<>(); System.out.println("==> For Loop Example."); for (int i = 0; i < linkedList.size(); i++) {     System.out.println(linkedList.get(i)); } 

Enhanced for loop

for (String temp : linkedList) {     System.out.println(temp); } 

While loop

int i = 0; while (i < linkedList.size()) {     System.out.println(linkedList.get(i));     i++; } 

Iterator

Iterator<String> iterator = linkedList.iterator(); while (iterator.hasNext()) {     System.out.println(iterator.next());  } 

collection stream() util (Java 8)

linkedList.forEach((temp) -> {     System.out.println(temp); }); 

One thing should be pointed out is that the running time of For Loop or While Loop is O(n square) because get(i) operation takes O(n) time(see this for details). The other 3 ways take linear time and performs better.

Answer 2

Linked list is guaranteed to act in sequential order.

From the documentation

An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.

iterator() Returns an iterator over the elements in this list in proper sequence.