Java ArrayList Methods

Lecture 69:-  Java ArrayList Methods

ArrayList in Java provides a wide range of methods to manipulate the list of elements it holds. Here are some of the commonly used methods of the ArrayList class:

1. Adding Elements:
   • add(E element): Appends the specified element to the end of the list.
   • add(int index, E element): Inserts the specified element at the specified position in the list.
2. Accessing Elements:
   • get(int index): Returns the element at the specified index.
   • set(int index, E element): Replaces the element at the specified index with the specified element.
3. Removing Elements:
   • remove(int index): Removes the element at the specified index from the list.
   • remove(Object o): Removes the first occurrence of the specified element from the list.
   • clear(): Removes all elements from the list.
4. Size and Checking Empty:
   • size(): Returns the number of elements in the list.
   • isEmpty(): Returns true if the list is empty, otherwise false.
5. Searching Elements:
   • contains(Object o): Returns true if the list contains the specified element, otherwise false.
   • indexOf(Object o): Returns the index of the first occurrence of the specified element, or -1 if not found.
   • lastIndexOf(Object o): Returns the index of the last occurrence of the specified element, or -1 if not found.
6. Sublist Operations:
   • subList(int fromIndex, int toIndex): Returns a new ArrayList containing elements from fromIndex (inclusive) to toIndex (exclusive).
7. Converting to Array:
   • toArray(): Converts the ArrayList to a regular array of objects.
   • toArray(T[] a): Converts the ArrayList to an array of the specified type T.
8. Iterating Over ArrayList:
   • You can use the enhanced for loop (for-each loop) or the traditional for loop to iterate over the elements in an ArrayList.

javaCopy code

import java.util.ArrayList; public class ArrayListMethodsExample {    public static void main(String[] args) {        ArrayList<Integer> numbers = new ArrayList<>();        // Adding elements        numbers.add(10);        numbers.add(20);        numbers.add(30);        // Accessing elements        int secondNumber = numbers.get(1); // 20        // Removing elements        numbers.remove(0); // Remove 10        // Size and checking empty        int size = numbers.size(); // 2        boolean isEmpty = numbers.isEmpty(); // false        // Searching elements        boolean contains30 = numbers.contains(30); // true        int index = numbers.indexOf(30); // 1        // Sublist operations        ArrayList<Integer> sublist = numbers.subList(0, 1); // [20]        // Converting to array        Integer[] numbersArray = numbers.toArray(new Integer[0]);    } }

These are just some of the many methods available in the ArrayList class. The Java ArrayList provides a rich set of operations to manage and manipulate collections of elements efficiently. For more details and additional methods, you can refer to the official Java documentation for the ArrayList class.