Shuffle or Randomize a list in Java
java
↳ util
↳ Collections
Syntax:
Collections.shuffle(list);
Examples:
Java
import java.util.*;
public class GFG {
public static void main(String[] args)
{
ArrayList<String> mylist = new ArrayList<String>();
mylist.add( "ide" );
mylist.add( "quiz" );
mylist.add( "geeksforgeeks" );
mylist.add( "quiz" );
mylist.add( "practice" );
mylist.add( "qa" );
System.out.println( "Original List : \n" + mylist);
Collections.shuffle(mylist);
System.out.println( "\nShuffled List : \n" + mylist);
}
}
|
Output:
Original List :
[ide, quiz, geeksforgeeks, quiz, practice, qa]
Shuffled List :
[ide, practice, quiz, qa, geeksforgeeks, quiz]
- Shuffling a list using user provided Random Object
Syntax:
Collections.shuffle(list, Random object);
Examples:
Java
import java.util.*;
public class GFG {
public static void main(String[] args)
{
ArrayList<String> mylist = new ArrayList<String>();
mylist.add( "ide" );
mylist.add( "quiz" );
mylist.add( "geeksforgeeks" );
mylist.add( "quiz" );
mylist.add( "practice" );
mylist.add( "qa" );
System.out.println( "Original List : \n" + mylist);
Collections.shuffle(mylist, new Random());
System.out.println( "\nShuffled List with Random() : \n"
+ mylist);
Collections.shuffle(mylist, new Random( 3 ));
System.out.println( "\nShuffled List with Random(3) : \n"
+ mylist);
Collections.shuffle(mylist, new Random( 5 ));
System.out.println( "\nShuffled List with Random(5) : \n"
+ mylist);
}
}
|
Output:
Original List :
[ide, quiz, geeksforgeeks, quiz, practice, qa]
Shuffled List with Random() :
[geeksforgeeks, practice, qa, ide, quiz, quiz]
Shuffled List with Random(3) :
[quiz, ide, practice, quiz, geeksforgeeks, qa]
Shuffled List with Random(5) :
[ide, quiz, geeksforgeeks, quiz, practice, qa]
Java
import java.util.Random;
import java.util.Arrays;
public class ShuffleRand
{
static void randomize( int arr[], int n)
{
Random r = new Random();
for ( int i = n- 1 ; i > 0 ; i--) {
int j = r.nextInt(i);
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
System.out.println(Arrays.toString(arr));
}
public static void main(String[] args)
{
int [] arr = { 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 };
int n = arr.length;
randomize (arr, n);
}
}
|
Output:
[5, 7, 1, 3, 6, 8, 4, 2]
Last Updated :
09 Sep, 2021
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