ArrayList

A resizable array implementation of the List interface from the Java Collections Framework. Allows dynamic resizing and provides methods to manipulate the stored elements. Supports a generic to hint the type of elements. Cannot hold primitive types, like int, char, etc. Wrapper classes are needed.

Methods

• add(int index, Object element)
  Inserts the given element at the specific position
• add(Object o)
  Appends the given element to the end
• addAll(Collection C)
  Appends all the elements from the given collection to the end of the original list, in such an order that the values are returned by the specified collection’s iterator.
• clear()
  Removes all the elements from any list.
• clone()
  Return a shallow copy of the instance
• contains(Object o)
  Returns if the list contains the specified element.
• forEach(Consumer<? super E> action)
  Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception.
• get(int index)
  Returns the element at the specified position
• indexOf(Object O)
  The index the first occurrence of a specific element is either returned or -1 in case the element is not in the list.
• isEmpty()
  Returns if the list is empty
• lastIndexOf(Object O)
  The index of the last occurrence of a specific element is either returned or -1 in case the element is not in the list.
• remove(int index)
  Removes the element at the specified position
• remove(Object o)
  Removes the first occurrence of the specified element, if it is present.
• removeRange(int fromIndex, int toIndex)
  Removes all of the elements whose index is between fromIndex, inclusive, and toIndex, exclusive.
• set(int index, E element)
  Replaces the element at the specified position with the given element.
• size()
  Returns the number of elements
• subList(int fromIndex, int toIndex)
  Returns a view of the portion between the specified fromIndex (inclusive) and toIndex (exclusive).
• toArray()
  Return an array containing all of the elements in the list in the correct order.

Complexity of Java ArrayList

Operation	Time complexity	Space complexity
Inserting Element in ArrayList
Removing Element from ArrayList
Traversing Elements in ArrayList
Replacing Elements in ArrayList