In this example we shall show you how to shuffle a List’s elements. This is provided by the shuffle(List list) API method of the Collections class. The Collections class provides static methods that operate on or return collections. The ArrayList is used as a List implementation, but the same API applies to any type of List implementation classes e.g. Vector etc. To shuffle the elements of a List one should perform the following steps:
- Create a new ArrayList.
- Populate the list with elements, with the
add(E e)API method of the ArrayList. - Shuffle the elements of the list, invoking the
shuffle(List list)API
method of the Collections. It will randomly permute the specified list using a default source of randomnes,
as described in the code snippet below.
package com.javacodegeeks.snippets.core;
import java.util.ArrayList;
import java.util.Collections;
public class ShuffleList {
public static void main(String[] args) {
/*
Please note that the same API applies to any type of
List implementation classes e.g. Vector etc
*/
// Create an ArrayList and populate it with elements
ArrayList arrayList = new ArrayList();
arrayList.add("element_1");
arrayList.add("element_2");
arrayList.add("element_3");
arrayList.add("element_4");
arrayList.add("element_5");
System.out.println("ArrayList elements : " + arrayList);
// static void shuffle(List list) method shuffles elements of the provided LIst
Collections.shuffle(arrayList);
System.out.println("ArrayList elements after shuffling : " + arrayList);
}
}
Output:
ArrayList elements : [element_1, element_2, element_3, element_4, element_5]
ArrayList elements after shuffling : [element_5, element_3, element_4, element_1, element_2]
This was an example of how to shuffle a List’s elements in Java.
