• Arraylist is a class that inherits the List interface
• To define a list --->

 ArrayList<String> groceryList = new ArrayList();

• To add items -->

 groceryList.add("apples");

• To print items from a list

groceryList.get(i)

• To change value at a particular index in list

groceryList.set(1,"kiwis");

• To remove an item as well as the index from the list

groceryList.remove(1);

• To check if a particular item is there in the list

groceryList.contains("apples");

• To find the index no of an item in the list

 groceryList.indexOf("apples")

• Arraylist can't handle primitive data types like integers,floats ,doubles etc. It can only handle classes like String. And for primitive data types
• Instead we use wrapper classes for primitive data types likes Integer Double etc.
• Then we add retrieve values like this

    integerList.add(Integer.valueOf(i*20));  
    System.out.println(integerList.get(i).intValue());
  //Or simply like this  as wrapping is done by java by itself in the background
      integerList.add(i * 10);
System.out.println(integerList.get(i));