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This article mainly introduces how to use the collectionsshuffle method in java, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

There is a static shuffle () method under the Java.util.Collections class, and the output of Arrays.asList () is passed to the constructor of ArrayList (), which creates an ArrayList that references the element of ia, so disrupting these references does not modify the array. However, if you use the results of Arrays.asList (ia) directly, this disruption will change the order of the ia. It is important to realize that the List object generated by Arrays.asList () uses the underlying array as its physical implementation. As long as you perform an operation that modifies the List, and you don't want the original array to be modified, you should create a copy in another container.

Collectionsshuffle method

1) staticvoidshuffle (Listlist) replaces the list with the default random source, and all replacements are roughly equal.

2) staticvoidshuffle (Listlist,Randomrand) replaces the specified list with the specified random source, and all permutations are roughly equal, assuming that the random source is fair.

To put it more colloquially, it is like shuffling cards, randomly disrupting the original order.

Note: given an integer array, there are two ways to convert it to a collection class with the Arrays.asList () method:

1) scrambling with Listlist=ArrayList (Arrays.asList (ia)) and shuffle () does not change the order of the underlying arrays.

2) using Listlist=Arrays.aslist (ia) and then scrambling with shuffle () will change the order of the underlying arrays.

Collectionsshuffle code example

Packageshit

Importjava.util.*

PublicclassModify {

Publicstaticvoidmain (String [] args) {

Randomrand=newRandom (47)

Integer [] ia= {0,1,2,3,4,5,6,7,8,9}

Listlist=newArrayList (Arrays.asList (ia))

System.out.println ("Beforeshufflig:" + list)

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