- Barajar una lista
Collections.shuffle() se usa para barajar listas en java.
Jerarquía de clases:
java
↳ util
↳ Collections
Sintaxis:
Collections.shuffle(list);
Ejemplos:
Java
// Java program to demonstrate working of shuffle()
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);
}
}
Producción:
Original List : [ide, quiz, geeksforgeeks, quiz, practice, qa] Shuffled List : [ide, practice, quiz, qa, geeksforgeeks, quiz]
-
Barajar una lista utilizando la sintaxis de objetos aleatorios proporcionada por el usuario :
Collections.shuffle(list, Random object);
Ejemplos:
Java
// Java program to demonstrate working of shuffle()
// with user provided source of randomness.
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);
// Here we use Random() to shuffle given list.
Collections.shuffle(mylist, new Random());
System.out.println("\nShuffled List with Random() : \n"
+ mylist);
// Here we use Random(3) to shuffle given list. Here 3
// is seed value for Random.
Collections.shuffle(mylist, new Random(3));
System.out.println("\nShuffled List with Random(3) : \n"
+ mylist);
// Here we use Random(5) to shuffle given list. Here 5
// is seed value for Random.
Collections.shuffle(mylist, new Random(5));
System.out.println("\nShuffled List with Random(5) : \n"
+ mylist);
}
}
Producción:
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]
- ¿Cómo escribir nuestro propio método Shuffle?
Podemos usar el algoritmo aleatorio de Fisher-Yates que funciona en tiempo O(n).
Java
// Java Program to shuffle a given array
import java.util.Random;
import java.util.Arrays;
public class ShuffleRand
{
// A Function to generate a random permutation of arr[]
static void randomize( int arr[], int n)
{
// Creating a object for Random class
Random r = new Random();
// Start from the last element and swap one by one. We don't
// need to run for the first element that's why i > 0
for (int i = n-1; i > 0; i--) {
// Pick a random index from 0 to i
int j = r.nextInt(i);
// Swap arr[i] with the element at random index
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
// Prints the random array
System.out.println(Arrays.toString(arr));
}
// Driver Program to test above function
public static void main(String[] args)
{
int[] arr = {1, 2, 3, 4, 5, 6, 7, 8};
int n = arr.length;
randomize (arr, n);
}
}
Producción:
[5, 7, 1, 3, 6, 8, 4, 2]
Publicación traducida automáticamente
Artículo escrito por RishabhPrabhu y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA