In this article, we will discuss how to reverse order of elements in List using Collections class’s utility reverse() method
Reversing order of elements of Java ArrayList
Method signature:
public static void reverse(List<Object> list);
ReverseArrayListContents.java
package in.bench.resources.java.collection;
import java.util.ArrayList;
import java.util.Collections;
public class ReverseArrayListContents {
public static void main(String[] args) {
// creating ArrayList object of type String
ArrayList<String> al = new ArrayList<String>();
// adding elements to ArrayList object
al.add("Narayan Murthy");
al.add("Dinesh");
al.add("Nandan Nilekeni");
al.add("Ashok Arora");
al.add("Shibulal");
al.add("Kris Gopalakrishnan");
al.add("Raghavan");
System.out.println("Insertion order:"
+ " Iterating ArrayList values\n");
// Iterating using enhanced for-loop
for(String str : al){
System.out.println(str);
}
// reverse ordering of ArrayList
// using Collections.reverse(al);
Collections.reverse(al);
System.out.println("\n\nReverse Insertion order:"
+ " after reversing using Collections.reverse(al)\n");
// Iterating using enhanced for-loop
for(String str : al){
System.out.println(str);
}
}
}
Output:
Insertion order: Iterating ArrayList values
Narayan Murthy
Dinesh
Nandan Nilekeni
Ashok Arora
Shibulal
Kris Gopalakrishnan
Raghavan
Reverse Insertion order: after reversing using Collections.reverse(al)
Raghavan
Kris Gopalakrishnan
Shibulal
Ashok Arora
Nandan Nilekeni
Dinesh
Narayan Murthy
Related Articles:
- Java – Collections class a utility class for Collection
- Java – Sorting ArrayList using Comparable and Comparator
- Java – Searching element from ArrayList using Binary Search Algorithm
- Java – How to Reverse order of elements in ArrayList ?
- Java – How to Reverse order of Comparator ?
- Java – How to count duplicate elements of ArrayList ?
- Java – How to swap elements of ArrayList ?
- Java – How to copy elements of one ArrayList to another List ?
- Java – How to shuffle elements of ArrayList ?
References:
- https://docs.oracle.com/javase/tutorial/collections/intro/
- https://docs.oracle.com/javase/tutorial/collections/interfaces/collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/tutorial/collections/interfaces/list.html
- https://docs.oracle.com/javase/7/docs/api/java/util/List.html
- https://docs.oracle.com/javase/tutorial/collections/interfaces/order.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collections.html
Happy Coding !!
Happy Learning !!