How to reverse an array in Java

In this article I will explain how to reverse an array in Java? A cluster is an information structure that contains a gathering of components. Regularly these components are each of similar information type, like a whole number or string. Exhibits are usually utilized in PC projects to coordinate information with the goal that a connected arrangement of qualities can be immediately arranged or looked. Every one of the things of the exhibit are put away at adjoining memory areas.

Now and then software engineers need to handle exhibits beginning with the last component, all things considered, it is consistently effective to turn around the cluster so the primary component is set at the last situation in the exhibit, and the subsequent component is put at the subsequent last situation in the exhibit, etc until the last component is at the main file.

We’ll see one or two methods for doing this utilizing unadulterated Java 8-based arrangements – a portion of those transform a current exhibit and some make another one.

Then, we’ll take a gander at two arrangements utilizing outside libraries — one utilizing Apache Commons Lang and one utilizing Google Guava.

What is Array Reverse in Java?

To carry out exhibit turn around in Java Programming, the cluster size and from there on the exhibit components must be entered by the client. In the following stage, the exhibit components are traded. A variable (temp) of a similar sort is made for setting the primary component in factor temp, then, at that point, the component coming last is set in the main, temp is put in the last, etc – the interaction proceeds till the whole cluster is switched.

In Java, generally crude kinds of exhibits – int, long, string and twofold clusters – are needed to be switched with the end goal of explicit codes. Apache center lang, which is an open source library ascribed to the Apache programming establishment, gives class ArrayUtils. This intriguing class is utilized in relationship with the java.util.Arrays class for playing with article and crude clusters in Java. The API gives simple to-utilize over-burden techniques for turning around various sorts of clusters in Java – be it int, log, twofold, float or article exhibits.

How to Reverse Array in Java with Examples

There are numerous strategies to switch an exhibit in Java. You might consider composing a capacity on your own that circles across the exhibit and continue to trade every one of the components until the full cluster is arranged. In one more strategy for exhibit invert in Java, a cluster can be changed over into an ArrayList, later which a particular code can be utilized for switching the ArrayList. One more technique for cluster invert in Java contains utilizing the Apache Commons ArrayUtils.reverse() program for switching any sort of Java exhibit. This technique can be over-burden for the reason for turning around short, long, int, byte, float, twofold or string type exhibits. Clients might get a kick out of the chance to carry out any technique to invert a cluster in java according to their decision and nature of the exhibit in the retribution.

Technique 1: Reverse Array in Place

In this basic method for switching a Java cluster, the calculation is made to circle over the exhibit and continues to trade the components until the midpoint is reached. As no extra cradles are utilized, this strategy for switching a cluster in Java is additionally alluded to as an exhibit set up.

for(int i=0; i<array.length/2; i++){  int j= array[i];  array[i] = array[array.length -i –1];  array[array.length -i –1] = j; }

The time intricacy of the above calculation is O(n/2). As such, it is O(N) as the cycle across the circle happens till its midpoint as it were. This strategy gives an ideal answer for interviewees as the excess two techniques are well-suited for useful purposes.

Technique 2 – Using an ArrayList

This specific strategy for cluster invert in Java changes over the given exhibit into an ArrayList and afterward uses the Collections.reverse() technique that takes up the things in the rundown and turns around the components in direct time. Varieties of int, string or different sorts can be switched with the assistance of this method.The following model portrays an inversion of a string type exhibit in Java:

//Simple Java Program to reverse a string array import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class ArrayReverse {    public static void main(String args[])  {      String[] arrayColor = {“Red”, “Green”, “Blue”, “Orange”,“Yellow”};      System.out.println(“Array Before: “ + Arrays.toString(arrayColor) );      List<String> arrayNewColor = Arrays.asList(arrayColor);            Collections.reverse(arrayNewColor);      String[] reversed = arrayNewColor.toArray(arrayColor);      System.out.println(“Array Reverse: “ + Arrays.toString(reversed) );    } }


Exhibit Before: [Red, Green, Blue, Orange, Yellow]

Exhibit Reverse: [Yellow, Orange, Blue, Green, Red]

As is obvious from the result given over, the first request of components has been turned around in the last cluster as returned by the toArray() technique for the List class.

Strategy 3 – By utilizing ArrayUtils.reverse()

Apache hall alludes is an assortment of various utility libraries utilized for compelling Java improvement. This library is frequently added of course by coders to their ventures with a perspective on supplementing JDK. The Apache Commons Lang offers class ArrayUtils that contains over-burden switch() techniques for the reason for turning around int, float just as item type clusters in Java. This specific strategy turns around some random cluster in its place; all in all, another exhibit isn’t made for the reasons for cluster invert in the Java code.

The accompanying code will suitably portray this strategy:

import java.util.Arrays; import org.apache.commons.lang3.ArrayUtils; public class Byarrayutilis {    public static void main(String args[]) {        String[] arraycolor = {“Red”, “Green”, “Blue”, “Orange”,“Yellow”};        System.out.println(“Array before: “ + Arrays.toString(arraycolor));        ArrayUtils.reverse(arraycolor);        System.out.println(“Array after: “ + Arrays.toString(arraycolor));    } }


Cluster Before: [Red, Green, Blue, Orange, Yellow]

Cluster Reverse: [Yellow, Orange, Blue, Green, Red]

<dependency>        <groupId>org.apache.commons</groupId>        <artifactId>commons-lang3</artifactId>        <version>3.4</version>    </dependency>

The ArrayUtils class has a place with Apache Commons Lang. Lodge lang3-3.4.jar must be added into the application’s class way for this strategy to happen. Then again, on account of Maven is being utilized then the accompanying reliance must be remembered for the pom.xml document.


The previously mentioned techniques go quite far in assisting coders with turning around int and String exhibit in Java. Switch exhibit in Java can be properly executed in accordance with the over three strategies. On the off chance that you need to address an inquiry question relating to a java program to turn around an exhibit then, at that point, utilize the set up calculation. The others strategies incorporate use of the ArrayList class and the utility strategy ArrayUtils.reverse() having a place with the Apache center lang library. Pick the strategy that applies to your converse cluster in java programming needs in the most ideal way!

Also Read: Read JSON file using Python

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