ArrayList Methods

Introduction to ArrayList Methods

  • Understand that ArrayList is a resizable array in Java, located in the java.util package.
  • Recognise that unlike arrays, ArrayLists can grow and shrink automatically.

ArrayList Declaration and Initialization

  • Declare an ArrayList with ArrayList<data-Type> listName = new ArrayList<>();.
  • Initialise an ArrayList with values using Arrays.asList(), such as ArrayList<Integer> numbers=new ArrayList<Integer>(Arrays.asList(1,2,3,4));.

Adding Elements

  • Use the add(element) method to append elements at the end of the ArrayList.
  • Use the add(index, element) method to insert an element at a specific index.

Accessing Elements

  • Use get(index) method to retrieve an element at a specific index.

Removing Elements

  • Implement remove(index) method to delete an element at a specified index.
  • Use remove(Object) to remove a specific object/element from the ArrayList.

Updating Elements

  • Use set(index, element) method to update an element at a specific index.

Checking if ArrayList is Empty

  • Apply isEmpty() that returns true if ArrayList is empty, false otherwise.

Size of ArrayList

  • Implement size() method to find the number of elements in an ArrayList.

Searching in ArrayList

  • Use the contains(object) method that returns true if the element is found, false otherwise.
  • Implement indexOf(Object) method to get the index of the first occurrence of an element in the ArrayList.

Converting ArrayList to Array

  • Use toArray() method to convert an ArrayList into an array.

Clearing ArrayList

  • Implement clear() method to remove all elements from the ArrayList.

Remember to import java.util.ArrayList and possibly java.util.Arrays before using ArrayLists in your programs.