Java Program to Shuffle a Given Array of Integers

Java Program to Shuffle a Given Array of Integers

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In the previous article, we have seen Java Program to Find the Smallest Number in an Array

In this article we are going to see how we can shuffle an array of integers in Java.

Java Program to Shuffle a Given Array of Integers

Array is a data structure which stores a fixed size sequential collection of values of single type. Where with every array elements/values memory location is associated. Each array elements have it’s own index where array index starts from 0.

In Array set of variables referenced by a single variable name and it’s array index position. It is also called as a container object which contains elements of similar type.

Declaration of an array:

dataType[] arrayName; (or)                              //Declaring an array
dataType []arrayName; (or)
dataType arr[];

Instantiation of an Array:

arrayName = new datatype[size];                    //Allocating memory to array

Combining both Statements in One:

dataType[] arrayName = new dataType[size] //Declaring and Instantiating array

Initialization of an Array:

arrayName[index-0]= arrayElement1             //Initializing the array

...

arrayName[index-s]= arrayElementS

Combining all Statements in One:

dataType arrayName[ ]={e1,e2,e3};               //declaration, instantiation and initialization

Let’s see different ways to shuffle an array of integers.

Method-1: Java Program to Shuffle a Given Array of Integers By Using Fisher-Yates Algorithm

Approach:

  • Create an array of integers with elements.
  • Display the array to the user.
  • Traverse through the array using a for loop
  • Swap the element at each location with a random element present in the array.
  • Display the array to the user.

Program:

import java.util.*;
import java.util.Scanner;

public class Main
{
    public static void main(String args[])
    {
        // Creating the array
        int arr[] = {12, 2, 34, 20, 54, 6, 52, 8, 9, 68};

        // Prints the array elements
        System.out.println("The array elements are "+Arrays.toString(arr));
        
        shuffle(arr);

        // Prints the array elements
        System.out.println("The array elements after shuffling "+Arrays.toString(arr));
    }
    
    // Funbction that shuffles the array elements
    static void shuffle(int arr[])
    {
        Random rand = new Random();
        int randomVariable, temp;
        for(int i=arr.length-1; i>=1;i-- )
        {
            // Finds a random number between 0 and the current location of array
            randomVariable= rand.nextInt(i+1);
            // Swaps the elements
            temp = arr[i];
            arr[i] = arr[randomVariable];
            arr[randomVariable] = temp;

        }
    }
}



Program:

The array elements are [12, 2, 34, 20, 54, 6, 52, 8, 9, 68]
The array elements after shuffling [20, 8, 2, 9, 68, 34, 54, 6, 12, 52]

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