You can replace an element of an ArrayList using the set() method of the Collections class. This method accepts two parameters an integer parameter indicating the index of the element to be replaced and an element to replace with.Example Live Demoimport java.util.ArrayList; public class ArrayListSample {    public static void main(String[] args) {       ArrayList list = new ArrayList();       list.add("JavaFx");       list.add("Java");       list.add("WebGL");       list.add("OpenCV");       System.out.println(list);       list.set(2, "HBase");       System.out.println(list);    } }Output[JavaFx, Java, WebGL, OpenCV] [JavaFx, Java, HBase, OpenCV]

To sort the contents of an ArrayList in descending orderCreate an ArrayList.Sort the contents of the ArrayList using the sort() method of the Collections class.Then, reverse array list using the reverse() method of the Collections class.Example:import java.util.ArrayList; import java.util.Collections; public class ArrayListSample {    public static void main(String[] args) {       ArrayList list = new ArrayList();       list.add("JavaFx");       list.add("Java");       list.add("WebGL");       list.add("OpenCV");       Collections.sort(list);       System.out.println(list);       Collections.reverse(list);       System.out.println(list);    } }Output:[Java, JavaFx, OpenCV, WebGL] [WebGL, OpenCV, JavaFx, Java]

You can sort an ArrayList using the sort() method of the Collections class this method accepts a list object as a parameter and sorts the contents of it in ascending order.Example:import java.util.ArrayList; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; public class ArrayListSample {    public static void main(String[] args) {       ArrayList list = new ArrayList();       list.add("JavaFx");       list.add("Java");       list.add("WebGL");       list.add("OpenCV");       Set set = new LinkedHashSet(list);       Collections.sort(list);       System.out.println(list);    } }Output:[Java, JavaFx, OpenCV, WebGL]

The synchronizedList(List list) method of the Collections class accepts a List object and returns a synchronized list backed by the specified list.Example:import java.util.ArrayList; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; public class ArrayListSample {    public static void main(String[] args){       ArrayList list = new ArrayList();       list.add("JavaFx");       list.add("Java");       list.add("WebGL");       list.add("OpenCV");       Set set = new LinkedHashSet(list);       Collections.synchronizedList(list);       System.out.println(list);    } }Output:[JavaFx, Java, WebGL, OpenCV]

The Collections class provides a method named reverse() this method accepts a list and reverses the order of elements in it.Example:import java.util.ArrayList; import java.util.Collections; import java.util.LinkedHashSet; import java.util.Set; public class Sample {    public static void main(String[] args){       ArrayList list = new ArrayList();       list.add("JavaFx");       list.add("Java");       list.add("WebGL");       list.add("OpenCV");       Set set = new LinkedHashSet(list);       System.out.println(set);       Collections.reverse(list);       System.out.println(list);    } }Output:[JavaFx, Java, WebGL, OpenCV] [OpenCV, WebGL, Java, JavaFx]

The removeLast() method of the java.util.LinkedList class removes and returns the last element of this list.Example:import java.util.*; public class LinkedListDemo {    public static void main(String[] args) {       LinkedList list = new LinkedList();       list.add("Hello");       list.add(2);       list.add("Chocolate");       list.add("10");       System.out.println("LinkedList:" + list);       System.out.println("Last element:" + list.removeLast());       System.out.println("LinkedList:" + list);    } }Output:LinkedList:[Hello, 2, Chocolate, 10] Last element:10 LinkedList:[Hello, 2, Chocolate]

The removeFirst() method of the java.util.LinkedList class removes and returns the first element from this list.Example:import java.util.*; public class LinkedListDemo {    public static void main(String[] args) {       LinkedList list = new LinkedList();       list.add("Hello");       list.add(2);       list.add("Chocolate");       list.add("10");       System.out.println("LinkedList:" + list);       System.out.println("First element:" + list.removeFirst());       System.out.println("LinkedList:" + list);    } }Output:LinkedList:[Hello, 2, Chocolate, 10] First element:Hello LinkedList:[2, Chocolate, 10]

The getLast() method of the class java.util.LinkedList returns the last element in this list.Example:import java.util.*; public class LinkedListDemo {    public static void main(String[] args) {       LinkedList list = new LinkedList();       list.add("Hello");       list.add(2);       list.add("Chocolate");       list.add("10");       System.out.println("LinkedList:" + list);       System.out.println("Last Element :" + list.getLast());    } }Output:LinkedList:[Hello, 2, Chocolate, 10] Last Element :10

The getFirst() method of the class java.util.LinkedList returns the first element of the current list. Example Live Demo import java.util.*; public class LinkedListDemo { public static void main(String[] args) { LinkedList list = new LinkedList(); list.add("Hello"); list.add(2); list.add("Chocolate"); list.add("10"); System.out.println("LinkedList:" + list); System.out.println("First Element :" + list.getFirst()); } } Output LinkedList:[Hello, 2, Chocolate, 10] First Element :Hello

The addLast(E e) method of the java.util.LinkedList class inserts the specified element at the end of this list.Example:import java.util.*; public class LinkedListDemo {    public static void main(String[] args) {       LinkedList list = new LinkedList();       list.add("Hello");       list.add(2);       list.add("Chocolate");       list.add("10");       System.out.println("LinkedList:" + list);       list.addLast("Element");       System.out.println("LinkedList:" + list);    } }Output:LinkedList:[Hello, 2, Chocolate, 10] LinkedList:[Hello, 2, Chocolate, 10, Element]