List

In Java, the List interface is a part of the java.util package and represents an ordered collection (also known as a sequence) of elements. Here’s the syntax and a list of commonly used methods in the List interface:

public interface List<E> extends Collection<E> {
    // Methods
}Code language: PHP (php)

Methods:

1. Adding Elements:
   • boolean add(E e): Appends the specified element to the end of this list (optional operation).
   • void add(int index, E element): Inserts the specified element at the specified position in this list (optional operation).
2. Removing Elements:
   • boolean remove(Object o): Removes the first occurrence of the specified element from this list, if it is present (optional operation).
   • E remove(int index): Removes the element at the specified position in this list (optional operation).
3. Accessing Elements:
   • E get(int index): Returns the element at the specified position in this list.
   • E set(int index, E element): Replaces the element at the specified position in this list with the specified element (optional operation).
4. Querying List Information:
   • int size(): Returns the number of elements in this list.
   • boolean isEmpty(): Returns true if this list contains no elements.
5. Searching and Checking:
   • boolean contains(Object o): Returns true if this list contains the specified element.
   • int indexOf(Object o): Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
6. Sublists:
   • List<E> subList(int fromIndex, int toIndex): Returns a view of the portion of this list between the specified fromIndex, inclusive, and toIndex, exclusive.
7. Bulk Operations:
   • boolean containsAll(Collection<?> c): Returns true if this list contains all of the elements of the specified collection.
   • boolean addAll(Collection<? extends E> c): Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection’s iterator (optional operation).
8. Conversion to Array:
   • Object[] toArray(): Returns an array containing all of the elements in this list in proper sequence.
9. Clearing the List:
   • void clear(): Removes all of the elements from this list (optional operation).

import java.util.*;
public class ListExample {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();

        // Adding elements
        list.add("Java");
        list.add("Python");
        list.add("C++");

        // Accessing elements
        System.out.println("Element at index 1: " + list.get(1));

        // Removing elements
        list.remove("Python");

        // Iterating over elements
        for (String language : list) {
            System.out.println(language);
        }

        // Checking if list contains an element
        System.out.println("List contains Java: " + list.contains("Java"));
    }
}