ArrayList

Features

• Initialise with initial capacity. 

           List<Integer> list = new ArrayList<>(100);
           But this will help if you have idea about initial size of ArrayList

• Initialise without initial capacity

           List<Integer> list = new ArrayList<>();

           Default it is initialised with size 10

• Index based search 

           list.get(13);

• Can be used only with Objects/Wrapper classes and not with primitives. 

          This is valid - List<Integer> list = new ArrayList<>(100);

          This is invalid - List<int> list = new ArrayList<>(100);

How to iterate ArrayList?

• For loop

List<Integer> list = new ArrayList<>();

for(int i =0; i<list.size(); i++){
    int element = list.get(i);

}

• Enhanced For Loop

List<Integer> list = new ArrayList<>();

for(int num : list){
    System.out.println(num);

}

• While loop

List<Integer> list = new ArrayList<>();

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

}

• Iterator

List<Integer> list = new ArrayList<>();

Iterator<Integer> iterator = list.iterator();

while (iterator.hasNext()){
    System.out.println(iterator.next());

}

• ListIterator

List<Integer> list = new ArrayList<>();

ListIterator<Integer> iterator = list.listIterator();

while (iterator.hasNext()){
    System.out.println(iterator.next());}