Collections – List – ArrayList and LinkedList:
So far we have already discussed regarding Set and Map. In this article we are going to discuss regarding Lists. There are two types of Lists – ArrayList and LinkedList – (HashSet here and HashMap here)
Difference Between ArrayList and LinkedList:
| ArrayList | LinkedList |
|---|---|
| ArrayList uses array to store the elements | LinkedList uses doubly linked list to store the elements |
| ArrayList needs to know the size or it will re-create when it needs to grow | LinkedList grows dynamically |
| ArrayList Manipulation is slow since it is an array | LinkedList Manipulation is fast |
When should we use ArrayList and When to use LinkedList:
ArrayList:
- When random access of elements are needed
- If we know the size of array ahead so we can allocate the memory
LinkedList:
- When we need more insertions/deletions
- When we do not know the size to be allocated
Example Program:
import java.util.List;
import java.util.LinkedList;
public class ListExample {
public static void main(String args[]){
List linkedList = new LinkedList();
//Inserting into linkedlist
for(int i=0; i<9; i++){
linkedList.add(i);
}
//Reading from LinkedList
for(Object l1: linkedList){
System.out.print(l1+" ");
}
//finding an element in linkedlist
for(int i=0; i<linkedList.size();i++){
if(linkedList.get(i).equals(3)){
System.out.println("Found");
}
}
//Removing from List
linkedList.remove(4);
//Reading from LinkedList after Removing
for(Object l1: linkedList){
System.out.print(l1+" ");
}
}
}
Output:
